code:
'use strict';

const { Duplex } = require('stream');

/**
 * Emits the `'close'` event on a stream.
 *
 * @param {Duplex} stream The stream.
 * @private
 */
function emitClose(stream) {
  stream.emit('close');
}

/**
 * The listener of the `'end'` event.
 *
 * @private
 */
function duplexOnEnd() {
  if (!this.destroyed && this._writableState.finished) {
    this.destroy();
  }
}

/**
 * The listener of the `'error'` event.
 *
 * @param {Error} err The error
 * @private
 */
function duplexOnError(err) {
  this.removeListener('error', duplexOnError);
  this.destroy();
  if (this.listenerCount('error') === 0) {
    // Do not suppress the throwing behavior.
    this.emit('error', err);
  }
}

/**
 * Wraps a `WebSocket` in a duplex stream.
 *
 * @param {WebSocket} ws The `WebSocket` to wrap
 * @param {Object} [options] The options for the `Duplex` constructor
 * @return {Duplex} The duplex stream
 * @public
 */
function createWebSocketStream(ws, options) {
  let resumeOnReceiverDrain = true;
  let terminateOnDestroy = true;

  function receiverOnDrain() {
    if (resumeOnReceiverDrain) ws._socket.resume();
  }

  if (ws.readyState === ws.CONNECTING) {
    ws.once('open', function open() {
      ws._receiver.removeAllListeners('drain');
      ws._receiver.on('drain', receiverOnDrain);
    });
  } else {
    ws._receiver.removeAllListeners('drain');
    ws._receiver.on('drain', receiverOnDrain);
  }

  const duplex = new Duplex({
    ...options,
    autoDestroy: false,
    emitClose: false,
    objectMode: false,
    writableObjectMode: false
  });

  ws.on('message', function message(msg) {
    if (!duplex.push(msg)) {
      resumeOnReceiverDrain = false;
      ws._socket.pause();
    }
  });

  ws.once('error', function error(err) {
    if (duplex.destroyed) return;

    // Prevent `ws.terminate()` from being called by `duplex._destroy()`.
    //
    // - If the `'error'` event is emitted before the `'open'` event, then
    //   `ws.terminate()` is a noop as no socket is assigned.
    // - Otherwise, the error is re-emitted by the listener of the `'error'`
    //   event of the `Receiver` object. The listener already closes the
    //   connection by calling `ws.close()`. This allows a close frame to be
    //   sent to the other peer. If `ws.terminate()` is called right after this,
    //   then the close frame might not be sent.
    terminateOnDestroy = false;
    duplex.destroy(err);
  });

  ws.once('close', function close() {
    if (duplex.destroyed) return;

    duplex.push(null);
  });

  duplex._destroy = function (err, callback) {
    if (ws.readyState === ws.CLOSED) {
      callback(err);
      process.nextTick(emitClose, duplex);
      return;
    }

    let called = false;

    ws.once('error', function error(err) {
      called = true;
      callback(err);
    });

    ws.once('close', function close() {
      if (!called) callback(err);
      process.nextTick(emitClose, duplex);
    });

    if (terminateOnDestroy) ws.terminate();
  };

  duplex._final = function (callback) {
    if (ws.readyState === ws.CONNECTING) {
      ws.once('open', function open() {
        duplex._final(callback);
      });
      return;
    }

    // If the value of the `_socket` property is `null` it means that `ws` is a
    // client websocket and the handshake failed. In fact, when this happens, a
    // socket is never assigned to the websocket. Wait for the `'error'` event
    // that will be emitted by the websocket.
    if (ws._socket === null) return;

    if (ws._socket._writableState.finished) {
      callback();
      if (duplex._readableState.endEmitted) duplex.destroy();
    } else {
      ws._socket.once('finish', function finish() {
        // `duplex` is not destroyed here because the `'end'` event will be
        // emitted on `duplex` after this `'finish'` event. The EOF signaling
        // `null` chunk is, in fact, pushed when the websocket emits `'close'`.
        callback();
      });
      ws.close();
    }
  };

  duplex._read = function () {
    if (
      (ws.readyState === ws.OPEN || ws.readyState === ws.CLOSING) &&
      !resumeOnReceiverDrain
    ) {
      resumeOnReceiverDrain = true;
      if (!ws._receiver._writableState.needDrain) ws._socket.resume();
    }
  };

  duplex._write = function (chunk, encoding, callback) {
    if (ws.readyState === ws.CONNECTING) {
      ws.once('open', function open() {
        duplex._write(chunk, encoding, callback);
      });
      return;
    }

    ws.send(chunk, callback);
  };

  duplex.on('end', duplexOnEnd);
  duplex.on('error', duplexOnError);
  return duplex;
}

module.exports = createWebSocketStream;


code:
'use strict';

/**
 * Checks if a status code is allowed in a close frame.
 *
 * @param {Number} code The status code
 * @return {Boolean} `true` if the status code is valid, else `false`
 * @public
 */
function isValidStatusCode(code) {
  return (
    (code >= 1000 &&
      code <= 1014 &&
      code !== 1004 &&
      code !== 1005 &&
      code !== 1006) ||
    (code >= 3000 && code <= 4999)
  );
}

/**
 * Checks if a given buffer contains only correct UTF-8.
 * Ported from https://www.cl.cam.ac.uk/%7Emgk25/ucs/utf8_check.c by
 * Markus Kuhn.
 *
 * @param {Buffer} buf The buffer to check
 * @return {Boolean} `true` if `buf` contains only correct UTF-8, else `false`
 * @public
 */
function _isValidUTF8(buf) {
  const len = buf.length;
  let i = 0;

  while (i < len) {
    if ((buf[i] & 0x80) === 0) {
      // 0xxxxxxx
      i++;
    } else if ((buf[i] & 0xe0) === 0xc0) {
      // 110xxxxx 10xxxxxx
      if (
        i + 1 === len ||
        (buf[i + 1] & 0xc0) !== 0x80 ||
        (buf[i] & 0xfe) === 0xc0 // Overlong
      ) {
        return false;
      }

      i += 2;
    } else if ((buf[i] & 0xf0) === 0xe0) {
      // 1110xxxx 10xxxxxx 10xxxxxx
      if (
        i + 2 >= len ||
        (buf[i + 1] & 0xc0) !== 0x80 ||
        (buf[i + 2] & 0xc0) !== 0x80 ||
        (buf[i] === 0xe0 && (buf[i + 1] & 0xe0) === 0x80) || // Overlong
        (buf[i] === 0xed && (buf[i + 1] & 0xe0) === 0xa0) // Surrogate (U+D800 - U+DFFF)
      ) {
        return false;
      }

      i += 3;
    } else if ((buf[i] & 0xf8) === 0xf0) {
      // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
      if (
        i + 3 >= len ||
        (buf[i + 1] & 0xc0) !== 0x80 ||
        (buf[i + 2] & 0xc0) !== 0x80 ||
        (buf[i + 3] & 0xc0) !== 0x80 ||
        (buf[i] === 0xf0 && (buf[i + 1] & 0xf0) === 0x80) || // Overlong
        (buf[i] === 0xf4 && buf[i + 1] > 0x8f) ||
        buf[i] > 0xf4 // > U+10FFFF
      ) {
        return false;
      }

      i += 4;
    } else {
      return false;
    }
  }

  return true;
}

try {
  let isValidUTF8 = require('utf-8-validate');

  /* istanbul ignore if */
  if (typeof isValidUTF8 === 'object') {
    isValidUTF8 = isValidUTF8.Validation.isValidUTF8; // utf-8-validate@<3.0.0
  }

  module.exports = {
    isValidStatusCode,
    isValidUTF8(buf) {
      return buf.length < 150 ? _isValidUTF8(buf) : isValidUTF8(buf);
    }
  };
} catch (e) /* istanbul ignore next */ {
  module.exports = {
    isValidStatusCode,
    isValidUTF8: _isValidUTF8
  };
}

license: mit


code:
/* eslint no-unused-vars: ["error", { "varsIgnorePattern": "^net|tls|https$" }] */

'use strict';

const EventEmitter = require('events');
const http = require('http');
const https = require('https');
const net = require('net');
const tls = require('tls');
const { createHash } = require('crypto');

const PerMessageDeflate = require('./permessage-deflate');
const WebSocket = require('./websocket');
const { format, parse } = require('./extension');
const { GUID, kWebSocket } = require('./constants');

const keyRegex = /^[+/0-9A-Za-z]{22}==$/;

const RUNNING = 0;
const CLOSING = 1;
const CLOSED = 2;

/**
 * Class representing a WebSocket server.
 *
 * @extends EventEmitter
 */
class WebSocketServer extends EventEmitter {
  /**
   * Create a `WebSocketServer` instance.
   *
   * @param {Object} options Configuration options
   * @param {Number} [options.backlog=511] The maximum length of the queue of
   *     pending connections
   * @param {Boolean} [options.clientTracking=true] Specifies whether or not to
   *     track clients
   * @param {Function} [options.handleProtocols] A hook to handle protocols
   * @param {String} [options.host] The hostname where to bind the server
   * @param {Number} [options.maxPayload=104857600] The maximum allowed message
   *     size
   * @param {Boolean} [options.noServer=false] Enable no server mode
   * @param {String} [options.path] Accept only connections matching this path
   * @param {(Boolean|Object)} [options.perMessageDeflate=false] Enable/disable
   *     permessage-deflate
   * @param {Number} [options.port] The port where to bind the server
   * @param {(http.Server|https.Server)} [options.server] A pre-created HTTP/S
   *     server to use
   * @param {Function} [options.verifyClient] A hook to reject connections
   * @param {Function} [callback] A listener for the `listening` event
   */
  constructor(options, callback) {
    super();

    options = {
      maxPayload: 100 * 1024 * 1024,
      perMessageDeflate: false,
      handleProtocols: null,
      clientTracking: true,
      verifyClient: null,
      noServer: false,
      backlog: null, // use default (511 as implemented in net.js)
      server: null,
      host: null,
      path: null,
      port: null,
      ...options
    };

    if (
      (options.port == null && !options.server && !options.noServer) ||
      (options.port != null && (options.server || options.noServer)) ||
      (options.server && options.noServer)
    ) {
      throw new TypeError(
        'One and only one of the "port", "server", or "noServer" options ' +
          'must be specified'
      );
    }

    if (options.port != null) {
      this._server = http.createServer((req, res) => {
        const body = http.STATUS_CODES[426];

        res.writeHead(426, {
          'Content-Length': body.length,
          'Content-Type': 'text/plain'
        });
        res.end(body);
      });
      this._server.listen(
        options.port,
        options.host,
        options.backlog,
        callback
      );
    } else if (options.server) {
      this._server = options.server;
    }

    if (this._server) {
      const emitConnection = this.emit.bind(this, 'connection');

      this._removeListeners = addListeners(this._server, {
        listening: this.emit.bind(this, 'listening'),
        error: this.emit.bind(this, 'error'),
        upgrade: (req, socket, head) => {
          this.handleUpgrade(req, socket, head, emitConnection);
        }
      });
    }

    if (options.perMessageDeflate === true) options.perMessageDeflate = {};
    if (options.clientTracking) this.clients = new Set();
    this.options = options;
    this._state = RUNNING;
  }

  /**
   * Returns the bound address, the address family name, and port of the server
   * as reported by the operating system if listening on an IP socket.
   * If the server is listening on a pipe or UNIX domain socket, the name is
   * returned as a string.
   *
   * @return {(Object|String|null)} The address of the server
   * @public
   */
  address() {
    if (this.options.noServer) {
      throw new Error('The server is operating in "noServer" mode');
    }

    if (!this._server) return null;
    return this._server.address();
  }

  /**
   * Close the server.
   *
   * @param {Function} [cb] Callback
   * @public
   */
  close(cb) {
    if (cb) this.once('close', cb);

    if (this._state === CLOSED) {
      process.nextTick(emitClose, this);
      return;
    }

    if (this._state === CLOSING) return;
    this._state = CLOSING;

    //
    // Terminate all associated clients.
    //
    if (this.clients) {
      for (const client of this.clients) client.terminate();
    }

    const server = this._server;

    if (server) {
      this._removeListeners();
      this._removeListeners = this._server = null;

      //
      // Close the http server if it was internally created.
      //
      if (this.options.port != null) {
        server.close(emitClose.bind(undefined, this));
        return;
      }
    }

    process.nextTick(emitClose, this);
  }

  /**
   * See if a given request should be handled by this server instance.
   *
   * @param {http.IncomingMessage} req Request object to inspect
   * @return {Boolean} `true` if the request is valid, else `false`
   * @public
   */
  shouldHandle(req) {
    if (this.options.path) {
      const index = req.url.indexOf('?');
      const pathname = index !== -1 ? req.url.slice(0, index) : req.url;

      if (pathname !== this.options.path) return false;
    }

    return true;
  }

  /**
   * Handle a HTTP Upgrade request.
   *
   * @param {http.IncomingMessage} req The request object
   * @param {(net.Socket|tls.Socket)} socket The network socket between the
   *     server and client
   * @param {Buffer} head The first packet of the upgraded stream
   * @param {Function} cb Callback
   * @public
   */
  handleUpgrade(req, socket, head, cb) {
    socket.on('error', socketOnError);

    const key =
      req.headers['sec-websocket-key'] !== undefined
        ? req.headers['sec-websocket-key'].trim()
        : false;
    const upgrade = req.headers.upgrade;
    const version = +req.headers['sec-websocket-version'];
    const extensions = {};

    if (
      req.method !== 'GET' ||
      upgrade === undefined ||
      upgrade.toLowerCase() !== 'websocket' ||
      !key ||
      !keyRegex.test(key) ||
      (version !== 8 && version !== 13) ||
      !this.shouldHandle(req)
    ) {
      return abortHandshake(socket, 400);
    }

    if (this.options.perMessageDeflate) {
      const perMessageDeflate = new PerMessageDeflate(
        this.options.perMessageDeflate,
        true,
        this.options.maxPayload
      );

      try {
        const offers = parse(req.headers['sec-websocket-extensions']);

        if (offers[PerMessageDeflate.extensionName]) {
          perMessageDeflate.accept(offers[PerMessageDeflate.extensionName]);
          extensions[PerMessageDeflate.extensionName] = perMessageDeflate;
        }
      } catch (err) {
        return abortHandshake(socket, 400);
      }
    }

    //
    // Optionally call external client verification handler.
    //
    if (this.options.verifyClient) {
      const info = {
        origin:
          req.headers[`${version === 8 ? 'sec-websocket-origin' : 'origin'}`],
        secure: !!(req.socket.authorized || req.socket.encrypted),
        req
      };

      if (this.options.verifyClient.length === 2) {
        this.options.verifyClient(info, (verified, code, message, headers) => {
          if (!verified) {
            return abortHandshake(socket, code || 401, message, headers);
          }

          this.completeUpgrade(key, extensions, req, socket, head, cb);
        });
        return;
      }

      if (!this.options.verifyClient(info)) return abortHandshake(socket, 401);
    }

    this.completeUpgrade(key, extensions, req, socket, head, cb);
  }

  /**
   * Upgrade the connection to WebSocket.
   *
   * @param {String} key The value of the `Sec-WebSocket-Key` header
   * @param {Object} extensions The accepted extensions
   * @param {http.IncomingMessage} req The request object
   * @param {(net.Socket|tls.Socket)} socket The network socket between the
   *     server and client
   * @param {Buffer} head The first packet of the upgraded stream
   * @param {Function} cb Callback
   * @throws {Error} If called more than once with the same socket
   * @private
   */
  completeUpgrade(key, extensions, req, socket, head, cb) {
    //
    // Destroy the socket if the client has already sent a FIN packet.
    //
    if (!socket.readable || !socket.writable) return socket.destroy();

    if (socket[kWebSocket]) {
      throw new Error(
        'server.handleUpgrade() was called more than once with the same ' +
          'socket, possibly due to a misconfiguration'
      );
    }

    if (this._state > RUNNING) return abortHandshake(socket, 503);

    const digest = createHash('sha1')
      .update(key + GUID)
      .digest('base64');

    const headers = [
      'HTTP/1.1 101 Switching Protocols',
      'Upgrade: websocket',
      'Connection: Upgrade',
      `Sec-WebSocket-Accept: ${digest}`
    ];

    const ws = new WebSocket(null);
    let protocol = req.headers['sec-websocket-protocol'];

    if (protocol) {
      protocol = protocol.split(',').map(trim);

      //
      // Optionally call external protocol selection handler.
      //
      if (this.options.handleProtocols) {
        protocol = this.options.handleProtocols(protocol, req);
      } else {
        protocol = protocol[0];
      }

      if (protocol) {
        headers.push(`Sec-WebSocket-Protocol: ${protocol}`);
        ws._protocol = protocol;
      }
    }

    if (extensions[PerMessageDeflate.extensionName]) {
      const params = extensions[PerMessageDeflate.extensionName].params;
      const value = format({
        [PerMessageDeflate.extensionName]: [params]
      });
      headers.push(`Sec-WebSocket-Extensions: ${value}`);
      ws._extensions = extensions;
    }

    //
    // Allow external modification/inspection of handshake headers.
    //
    this.emit('headers', headers, req);

    socket.write(headers.concat('\r\n').join('\r\n'));
    socket.removeListener('error', socketOnError);

    ws.setSocket(socket, head, this.options.maxPayload);

    if (this.clients) {
      this.clients.add(ws);
      ws.on('close', () => this.clients.delete(ws));
    }

    cb(ws, req);
  }
}

module.exports = WebSocketServer;

/**
 * Add event listeners on an `EventEmitter` using a map of <event, listener>
 * pairs.
 *
 * @param {EventEmitter} server The event emitter
 * @param {Object.<String, Function>} map The listeners to add
 * @return {Function} A function that will remove the added listeners when
 *     called
 * @private
 */
function addListeners(server, map) {
  for (const event of Object.keys(map)) server.on(event, map[event]);

  return function removeListeners() {
    for (const event of Object.keys(map)) {
      server.removeListener(event, map[event]);
    }
  };
}

/**
 * Emit a `'close'` event on an `EventEmitter`.
 *
 * @param {EventEmitter} server The event emitter
 * @private
 */
function emitClose(server) {
  server._state = CLOSED;
  server.emit('close');
}

/**
 * Handle premature socket errors.
 *
 * @private
 */
function socketOnError() {
  this.destroy();
}

/**
 * Close the connection when preconditions are not fulfilled.
 *
 * @param {(net.Socket|tls.Socket)} socket The socket of the upgrade request
 * @param {Number} code The HTTP response status code
 * @param {String} [message] The HTTP response body
 * @param {Object} [headers] Additional HTTP response headers
 * @private
 */
function abortHandshake(socket, code, message, headers) {
  if (socket.writable) {
    message = message || http.STATUS_CODES[code];
    headers = {
      Connection: 'close',
      'Content-Type': 'text/html',
      'Content-Length': Buffer.byteLength(message),
      ...headers
    };

    socket.write(
      `HTTP/1.1 ${code} ${http.STATUS_CODES[code]}\r\n` +
        Object.keys(headers)
          .map((h) => `${h}: ${headers[h]}`)
          .join('\r\n') +
        '\r\n\r\n' +
        message
    );
  }

  socket.removeListener('error', socketOnError);
  socket.destroy();
}

/**
 * Remove whitespace characters from both ends of a string.
 *
 * @param {String} str The string
 * @return {String} A new string representing `str` stripped of whitespace
 *     characters from both its beginning and end
 * @private
 */
function trim(str) {
  return str.trim();
}


code:
/* eslint no-unused-vars: ["error", { "varsIgnorePattern": "^Readable$" }] */

'use strict';

const EventEmitter = require('events');
const https = require('https');
const http = require('http');
const net = require('net');
const tls = require('tls');
const { randomBytes, createHash } = require('crypto');
const { Readable } = require('stream');
const { URL } = require('url');

const PerMessageDeflate = require('./permessage-deflate');
const Receiver = require('./receiver');
const Sender = require('./sender');
const {
  BINARY_TYPES,
  EMPTY_BUFFER,
  GUID,
  kStatusCode,
  kWebSocket,
  NOOP
} = require('./constants');
const { addEventListener, removeEventListener } = require('./event-target');
const { format, parse } = require('./extension');
const { toBuffer } = require('./buffer-util');

const readyStates = ['CONNECTING', 'OPEN', 'CLOSING', 'CLOSED'];
const protocolVersions = [8, 13];
const closeTimeout = 30 * 1000;

/**
 * Class representing a WebSocket.
 *
 * @extends EventEmitter
 */
class WebSocket extends EventEmitter {
  /**
   * Create a new `WebSocket`.
   *
   * @param {(String|URL)} address The URL to which to connect
   * @param {(String|String[])} [protocols] The subprotocols
   * @param {Object} [options] Connection options
   */
  constructor(address, protocols, options) {
    super();

    this._binaryType = BINARY_TYPES[0];
    this._closeCode = 1006;
    this._closeFrameReceived = false;
    this._closeFrameSent = false;
    this._closeMessage = '';
    this._closeTimer = null;
    this._extensions = {};
    this._protocol = '';
    this._readyState = WebSocket.CONNECTING;
    this._receiver = null;
    this._sender = null;
    this._socket = null;

    if (address !== null) {
      this._bufferedAmount = 0;
      this._isServer = false;
      this._redirects = 0;

      if (Array.isArray(protocols)) {
        protocols = protocols.join(', ');
      } else if (typeof protocols === 'object' && protocols !== null) {
        options = protocols;
        protocols = undefined;
      }

      initAsClient(this, address, protocols, options);
    } else {
      this._isServer = true;
    }
  }

  /**
   * This deviates from the WHATWG interface since ws doesn't support the
   * required default "blob" type (instead we define a custom "nodebuffer"
   * type).
   *
   * @type {String}
   */
  get binaryType() {
    return this._binaryType;
  }

  set binaryType(type) {
    if (!BINARY_TYPES.includes(type)) return;

    this._binaryType = type;

    //
    // Allow to change `binaryType` on the fly.
    //
    if (this._receiver) this._receiver._binaryType = type;
  }

  /**
   * @type {Number}
   */
  get bufferedAmount() {
    if (!this._socket) return this._bufferedAmount;

    return this._socket._writableState.length + this._sender._bufferedBytes;
  }

  /**
   * @type {String}
   */
  get extensions() {
    return Object.keys(this._extensions).join();
  }

  /**
   * @type {Function}
   */
  /* istanbul ignore next */
  get onclose() {
    return undefined;
  }

  /* istanbul ignore next */
  set onclose(listener) {}

  /**
   * @type {Function}
   */
  /* istanbul ignore next */
  get onerror() {
    return undefined;
  }

  /* istanbul ignore next */
  set onerror(listener) {}

  /**
   * @type {Function}
   */
  /* istanbul ignore next */
  get onopen() {
    return undefined;
  }

  /* istanbul ignore next */
  set onopen(listener) {}

  /**
   * @type {Function}
   */
  /* istanbul ignore next */
  get onmessage() {
    return undefined;
  }

  /* istanbul ignore next */
  set onmessage(listener) {}

  /**
   * @type {String}
   */
  get protocol() {
    return this._protocol;
  }

  /**
   * @type {Number}
   */
  get readyState() {
    return this._readyState;
  }

  /**
   * @type {String}
   */
  get url() {
    return this._url;
  }

  /**
   * Set up the socket and the internal resources.
   *
   * @param {(net.Socket|tls.Socket)} socket The network socket between the
   *     server and client
   * @param {Buffer} head The first packet of the upgraded stream
   * @param {Number} [maxPayload=0] The maximum allowed message size
   * @private
   */
  setSocket(socket, head, maxPayload) {
    const receiver = new Receiver(
      this.binaryType,
      this._extensions,
      this._isServer,
      maxPayload
    );

    this._sender = new Sender(socket, this._extensions);
    this._receiver = receiver;
    this._socket = socket;

    receiver[kWebSocket] = this;
    socket[kWebSocket] = this;

    receiver.on('conclude', receiverOnConclude);
    receiver.on('drain', receiverOnDrain);
    receiver.on('error', receiverOnError);
    receiver.on('message', receiverOnMessage);
    receiver.on('ping', receiverOnPing);
    receiver.on('pong', receiverOnPong);

    socket.setTimeout(0);
    socket.setNoDelay();

    if (head.length > 0) socket.unshift(head);

    socket.on('close', socketOnClose);
    socket.on('data', socketOnData);
    socket.on('end', socketOnEnd);
    socket.on('error', socketOnError);

    this._readyState = WebSocket.OPEN;
    this.emit('open');
  }

  /**
   * Emit the `'close'` event.
   *
   * @private
   */
  emitClose() {
    if (!this._socket) {
      this._readyState = WebSocket.CLOSED;
      this.emit('close', this._closeCode, this._closeMessage);
      return;
    }

    if (this._extensions[PerMessageDeflate.extensionName]) {
      this._extensions[PerMessageDeflate.extensionName].cleanup();
    }

    this._receiver.removeAllListeners();
    this._readyState = WebSocket.CLOSED;
    this.emit('close', this._closeCode, this._closeMessage);
  }

  /**
   * Start a closing handshake.
   *
   *          +----------+   +-----------+   +----------+
   *     - - -|ws.close()|-->|close frame|-->|ws.close()|- - -
   *    |     +----------+   +-----------+   +----------+     |
   *          +----------+   +-----------+         |
   * CLOSING  |ws.close()|<--|close frame|<--+-----+       CLOSING
   *          +----------+   +-----------+   |
   *    |           |                        |   +---+        |
   *                +------------------------+-->|fin| - - - -
   *    |         +---+                      |   +---+
   *     - - - - -|fin|<---------------------+
   *              +---+
   *
   * @param {Number} [code] Status code explaining why the connection is closing
   * @param {String} [data] A string explaining why the connection is closing
   * @public
   */
  close(code, data) {
    if (this.readyState === WebSocket.CLOSED) return;
    if (this.readyState === WebSocket.CONNECTING) {
      const msg = 'WebSocket was closed before the connection was established';
      return abortHandshake(this, this._req, msg);
    }

    if (this.readyState === WebSocket.CLOSING) {
      if (
        this._closeFrameSent &&
        (this._closeFrameReceived || this._receiver._writableState.errorEmitted)
      ) {
        this._socket.end();
      }

      return;
    }

    this._readyState = WebSocket.CLOSING;
    this._sender.close(code, data, !this._isServer, (err) => {
      //
      // This error is handled by the `'error'` listener on the socket. We only
      // want to know if the close frame has been sent here.
      //
      if (err) return;

      this._closeFrameSent = true;

      if (
        this._closeFrameReceived ||
        this._receiver._writableState.errorEmitted
      ) {
        this._socket.end();
      }
    });

    //
    // Specify a timeout for the closing handshake to complete.
    //
    this._closeTimer = setTimeout(
      this._socket.destroy.bind(this._socket),
      closeTimeout
    );
  }

  /**
   * Send a ping.
   *
   * @param {*} [data] The data to send
   * @param {Boolean} [mask] Indicates whether or not to mask `data`
   * @param {Function} [cb] Callback which is executed when the ping is sent
   * @public
   */
  ping(data, mask, cb) {
    if (this.readyState === WebSocket.CONNECTING) {
      throw new Error('WebSocket is not open: readyState 0 (CONNECTING)');
    }

    if (typeof data === 'function') {
      cb = data;
      data = mask = undefined;
    } else if (typeof mask === 'function') {
      cb = mask;
      mask = undefined;
    }

    if (typeof data === 'number') data = data.toString();

    if (this.readyState !== WebSocket.OPEN) {
      sendAfterClose(this, data, cb);
      return;
    }

    if (mask === undefined) mask = !this._isServer;
    this._sender.ping(data || EMPTY_BUFFER, mask, cb);
  }

  /**
   * Send a pong.
   *
   * @param {*} [data] The data to send
   * @param {Boolean} [mask] Indicates whether or not to mask `data`
   * @param {Function} [cb] Callback which is executed when the pong is sent
   * @public
   */
  pong(data, mask, cb) {
    if (this.readyState === WebSocket.CONNECTING) {
      throw new Error('WebSocket is not open: readyState 0 (CONNECTING)');
    }

    if (typeof data === 'function') {
      cb = data;
      data = mask = undefined;
    } else if (typeof mask === 'function') {
      cb = mask;
      mask = undefined;
    }

    if (typeof data === 'number') data = data.toString();

    if (this.readyState !== WebSocket.OPEN) {
      sendAfterClose(this, data, cb);
      return;
    }

    if (mask === undefined) mask = !this._isServer;
    this._sender.pong(data || EMPTY_BUFFER, mask, cb);
  }

  /**
   * Send a data message.
   *
   * @param {*} data The message to send
   * @param {Object} [options] Options object
   * @param {Boolean} [options.compress] Specifies whether or not to compress
   *     `data`
   * @param {Boolean} [options.binary] Specifies whether `data` is binary or
   *     text
   * @param {Boolean} [options.fin=true] Specifies whether the fragment is the
   *     last one
   * @param {Boolean} [options.mask] Specifies whether or not to mask `data`
   * @param {Function} [cb] Callback which is executed when data is written out
   * @public
   */
  send(data, options, cb) {
    if (this.readyState === WebSocket.CONNECTING) {
      throw new Error('WebSocket is not open: readyState 0 (CONNECTING)');
    }

    if (typeof options === 'function') {
      cb = options;
      options = {};
    }

    if (typeof data === 'number') data = data.toString();

    if (this.readyState !== WebSocket.OPEN) {
      sendAfterClose(this, data, cb);
      return;
    }

    const opts = {
      binary: typeof data !== 'string',
      mask: !this._isServer,
      compress: true,
      fin: true,
      ...options
    };

    if (!this._extensions[PerMessageDeflate.extensionName]) {
      opts.compress = false;
    }

    this._sender.send(data || EMPTY_BUFFER, opts, cb);
  }

  /**
   * Forcibly close the connection.
   *
   * @public
   */
  terminate() {
    if (this.readyState === WebSocket.CLOSED) return;
    if (this.readyState === WebSocket.CONNECTING) {
      const msg = 'WebSocket was closed before the connection was established';
      return abortHandshake(this, this._req, msg);
    }

    if (this._socket) {
      this._readyState = WebSocket.CLOSING;
      this._socket.destroy();
    }
  }
}

/**
 * @constant {Number} CONNECTING
 * @memberof WebSocket
 */
Object.defineProperty(WebSocket, 'CONNECTING', {
  enumerable: true,
  value: readyStates.indexOf('CONNECTING')
});

/**
 * @constant {Number} CONNECTING
 * @memberof WebSocket.prototype
 */
Object.defineProperty(WebSocket.prototype, 'CONNECTING', {
  enumerable: true,
  value: readyStates.indexOf('CONNECTING')
});

/**
 * @constant {Number} OPEN
 * @memberof WebSocket
 */
Object.defineProperty(WebSocket, 'OPEN', {
  enumerable: true,
  value: readyStates.indexOf('OPEN')
});

/**
 * @constant {Number} OPEN
 * @memberof WebSocket.prototype
 */
Object.defineProperty(WebSocket.prototype, 'OPEN', {
  enumerable: true,
  value: readyStates.indexOf('OPEN')
});

/**
 * @constant {Number} CLOSING
 * @memberof WebSocket
 */
Object.defineProperty(WebSocket, 'CLOSING', {
  enumerable: true,
  value: readyStates.indexOf('CLOSING')
});

/**
 * @constant {Number} CLOSING
 * @memberof WebSocket.prototype
 */
Object.defineProperty(WebSocket.prototype, 'CLOSING', {
  enumerable: true,
  value: readyStates.indexOf('CLOSING')
});

/**
 * @constant {Number} CLOSED
 * @memberof WebSocket
 */
Object.defineProperty(WebSocket, 'CLOSED', {
  enumerable: true,
  value: readyStates.indexOf('CLOSED')
});

/**
 * @constant {Number} CLOSED
 * @memberof WebSocket.prototype
 */
Object.defineProperty(WebSocket.prototype, 'CLOSED', {
  enumerable: true,
  value: readyStates.indexOf('CLOSED')
});

[
  'binaryType',
  'bufferedAmount',
  'extensions',
  'protocol',
  'readyState',
  'url'
].forEach((property) => {
  Object.defineProperty(WebSocket.prototype, property, { enumerable: true });
});

//
// Add the `onopen`, `onerror`, `onclose`, and `onmessage` attributes.
// See https://html.spec.whatwg.org/multipage/comms.html#the-websocket-interface
//
['open', 'error', 'close', 'message'].forEach((method) => {
  Object.defineProperty(WebSocket.prototype, `on${method}`, {
    enumerable: true,
    get() {
      const listeners = this.listeners(method);
      for (let i = 0; i < listeners.length; i++) {
        if (listeners[i]._listener) return listeners[i]._listener;
      }

      return undefined;
    },
    set(listener) {
      const listeners = this.listeners(method);
      for (let i = 0; i < listeners.length; i++) {
        //
        // Remove only the listeners added via `addEventListener`.
        //
        if (listeners[i]._listener) this.removeListener(method, listeners[i]);
      }
      this.addEventListener(method, listener);
    }
  });
});

WebSocket.prototype.addEventListener = addEventListener;
WebSocket.prototype.removeEventListener = removeEventListener;

module.exports = WebSocket;

/**
 * Initialize a WebSocket client.
 *
 * @param {WebSocket} websocket The client to initialize
 * @param {(String|URL)} address The URL to which to connect
 * @param {String} [protocols] The subprotocols
 * @param {Object} [options] Connection options
 * @param {(Boolean|Object)} [options.perMessageDeflate=true] Enable/disable
 *     permessage-deflate
 * @param {Number} [options.handshakeTimeout] Timeout in milliseconds for the
 *     handshake request
 * @param {Number} [options.protocolVersion=13] Value of the
 *     `Sec-WebSocket-Version` header
 * @param {String} [options.origin] Value of the `Origin` or
 *     `Sec-WebSocket-Origin` header
 * @param {Number} [options.maxPayload=104857600] The maximum allowed message
 *     size
 * @param {Boolean} [options.followRedirects=false] Whether or not to follow
 *     redirects
 * @param {Number} [options.maxRedirects=10] The maximum number of redirects
 *     allowed
 * @private
 */
function initAsClient(websocket, address, protocols, options) {
  const opts = {
    protocolVersion: protocolVersions[1],
    maxPayload: 100 * 1024 * 1024,
    perMessageDeflate: true,
    followRedirects: false,
    maxRedirects: 10,
    ...options,
    createConnection: undefined,
    socketPath: undefined,
    hostname: undefined,
    protocol: undefined,
    timeout: undefined,
    method: undefined,
    host: undefined,
    path: undefined,
    port: undefined
  };

  if (!protocolVersions.includes(opts.protocolVersion)) {
    throw new RangeError(
      `Unsupported protocol version: ${opts.protocolVersion} ` +
        `(supported versions: ${protocolVersions.join(', ')})`
    );
  }

  let parsedUrl;

  if (address instanceof URL) {
    parsedUrl = address;
    websocket._url = address.href;
  } else {
    parsedUrl = new URL(address);
    websocket._url = address;
  }

  const isUnixSocket = parsedUrl.protocol === 'ws+unix:';

  if (!parsedUrl.host && (!isUnixSocket || !parsedUrl.pathname)) {
    const err = new Error(`Invalid URL: ${websocket.url}`);

    if (websocket._redirects === 0) {
      throw err;
    } else {
      emitErrorAndClose(websocket, err);
      return;
    }
  }

  const isSecure =
    parsedUrl.protocol === 'wss:' || parsedUrl.protocol === 'https:';
  const defaultPort = isSecure ? 443 : 80;
  const key = randomBytes(16).toString('base64');
  const get = isSecure ? https.get : http.get;
  let perMessageDeflate;

  opts.createConnection = isSecure ? tlsConnect : netConnect;
  opts.defaultPort = opts.defaultPort || defaultPort;
  opts.port = parsedUrl.port || defaultPort;
  opts.host = parsedUrl.hostname.startsWith('[')
    ? parsedUrl.hostname.slice(1, -1)
    : parsedUrl.hostname;
  opts.headers = {
    'Sec-WebSocket-Version': opts.protocolVersion,
    'Sec-WebSocket-Key': key,
    Connection: 'Upgrade',
    Upgrade: 'websocket',
    ...opts.headers
  };
  opts.path = parsedUrl.pathname + parsedUrl.search;
  opts.timeout = opts.handshakeTimeout;

  if (opts.perMessageDeflate) {
    perMessageDeflate = new PerMessageDeflate(
      opts.perMessageDeflate !== true ? opts.perMessageDeflate : {},
      false,
      opts.maxPayload
    );
    opts.headers['Sec-WebSocket-Extensions'] = format({
      [PerMessageDeflate.extensionName]: perMessageDeflate.offer()
    });
  }
  if (protocols) {
    opts.headers['Sec-WebSocket-Protocol'] = protocols;
  }
  if (opts.origin) {
    if (opts.protocolVersion < 13) {
      opts.headers['Sec-WebSocket-Origin'] = opts.origin;
    } else {
      opts.headers.Origin = opts.origin;
    }
  }
  if (parsedUrl.username || parsedUrl.password) {
    opts.auth = `${parsedUrl.username}:${parsedUrl.password}`;
  }

  if (isUnixSocket) {
    const parts = opts.path.split(':');

    opts.socketPath = parts[0];
    opts.path = parts[1];
  }

  if (opts.followRedirects) {
    if (websocket._redirects === 0) {
      websocket._originalUnixSocket = isUnixSocket;
      websocket._originalSecure = isSecure;
      websocket._originalHostOrSocketPath = isUnixSocket
        ? opts.socketPath
        : parsedUrl.host;

      const headers = options && options.headers;

      //
      // Shallow copy the user provided options so that headers can be changed
      // without mutating the original object.
      //
      options = { ...options, headers: {} };

      if (headers) {
        for (const [key, value] of Object.entries(headers)) {
          options.headers[key.toLowerCase()] = value;
        }
      }
    } else {
      const isSameHost = isUnixSocket
        ? websocket._originalUnixSocket
          ? opts.socketPath === websocket._originalHostOrSocketPath
          : false
        : websocket._originalUnixSocket
        ? false
        : parsedUrl.host === websocket._originalHostOrSocketPath;

      if (!isSameHost || (websocket._originalSecure && !isSecure)) {
        //
        // Match curl 7.77.0 behavior and drop the following headers. These
        // headers are also dropped when following a redirect to a subdomain.
        //
        delete opts.headers.authorization;
        delete opts.headers.cookie;

        if (!isSameHost) delete opts.headers.host;

        opts.auth = undefined;
      }
    }

    //
    // Match curl 7.77.0 behavior and make the first `Authorization` header win.
    // If the `Authorization` header is set, then there is nothing to do as it
    // will take precedence.
    //
    if (opts.auth && !options.headers.authorization) {
      options.headers.authorization =
        'Basic ' + Buffer.from(opts.auth).toString('base64');
    }
  }

  let req = (websocket._req = get(opts));

  if (opts.timeout) {
    req.on('timeout', () => {
      abortHandshake(websocket, req, 'Opening handshake has timed out');
    });
  }

  req.on('error', (err) => {
    if (req === null || req.aborted) return;

    req = websocket._req = null;
    emitErrorAndClose(websocket, err);
  });

  req.on('response', (res) => {
    const location = res.headers.location;
    const statusCode = res.statusCode;

    if (
      location &&
      opts.followRedirects &&
      statusCode >= 300 &&
      statusCode < 400
    ) {
      if (++websocket._redirects > opts.maxRedirects) {
        abortHandshake(websocket, req, 'Maximum redirects exceeded');
        return;
      }

      req.abort();

      let addr;

      try {
        addr = new URL(location, address);
      } catch (err) {
        emitErrorAndClose(websocket, err);
        return;
      }

      initAsClient(websocket, addr, protocols, options);
    } else if (!websocket.emit('unexpected-response', req, res)) {
      abortHandshake(
        websocket,
        req,
        `Unexpected server response: ${res.statusCode}`
      );
    }
  });

  req.on('upgrade', (res, socket, head) => {
    websocket.emit('upgrade', res);

    //
    // The user may have closed the connection from a listener of the `upgrade`
    // event.
    //
    if (websocket.readyState !== WebSocket.CONNECTING) return;

    req = websocket._req = null;

    const upgrade = res.headers.upgrade;

    if (upgrade === undefined || upgrade.toLowerCase() !== 'websocket') {
      abortHandshake(websocket, socket, 'Invalid Upgrade header');
      return;
    }

    const digest = createHash('sha1')
      .update(key + GUID)
      .digest('base64');

    if (res.headers['sec-websocket-accept'] !== digest) {
      abortHandshake(websocket, socket, 'Invalid Sec-WebSocket-Accept header');
      return;
    }

    const serverProt = res.headers['sec-websocket-protocol'];
    const protList = (protocols || '').split(/, */);
    let protError;

    if (!protocols && serverProt) {
      protError = 'Server sent a subprotocol but none was requested';
    } else if (protocols && !serverProt) {
      protError = 'Server sent no subprotocol';
    } else if (serverProt && !protList.includes(serverProt)) {
      protError = 'Server sent an invalid subprotocol';
    }

    if (protError) {
      abortHandshake(websocket, socket, protError);
      return;
    }

    if (serverProt) websocket._protocol = serverProt;

    const secWebSocketExtensions = res.headers['sec-websocket-extensions'];

    if (secWebSocketExtensions !== undefined) {
      if (!perMessageDeflate) {
        const message =
          'Server sent a Sec-WebSocket-Extensions header but no extension ' +
          'was requested';
        abortHandshake(websocket, socket, message);
        return;
      }

      let extensions;

      try {
        extensions = parse(secWebSocketExtensions);
      } catch (err) {
        const message = 'Invalid Sec-WebSocket-Extensions header';
        abortHandshake(websocket, socket, message);
        return;
      }

      const extensionNames = Object.keys(extensions);

      if (extensionNames.length) {
        if (
          extensionNames.length !== 1 ||
          extensionNames[0] !== PerMessageDeflate.extensionName
        ) {
          const message =
            'Server indicated an extension that was not requested';
          abortHandshake(websocket, socket, message);
          return;
        }

        try {
          perMessageDeflate.accept(extensions[PerMessageDeflate.extensionName]);
        } catch (err) {
          const message = 'Invalid Sec-WebSocket-Extensions header';
          abortHandshake(websocket, socket, message);
          return;
        }

        websocket._extensions[PerMessageDeflate.extensionName] =
          perMessageDeflate;
      }
    }

    websocket.setSocket(socket, head, opts.maxPayload);
  });
}

/**
 * Emit the `'error'` and `'close'` event.
 *
 * @param {WebSocket} websocket The WebSocket instance
 * @param {Error} The error to emit
 * @private
 */
function emitErrorAndClose(websocket, err) {
  websocket._readyState = WebSocket.CLOSING;
  websocket.emit('error', err);
  websocket.emitClose();
}

/**
 * Create a `net.Socket` and initiate a connection.
 *
 * @param {Object} options Connection options
 * @return {net.Socket} The newly created socket used to start the connection
 * @private
 */
function netConnect(options) {
  options.path = options.socketPath;
  return net.connect(options);
}

/**
 * Create a `tls.TLSSocket` and initiate a connection.
 *
 * @param {Object} options Connection options
 * @return {tls.TLSSocket} The newly created socket used to start the connection
 * @private
 */
function tlsConnect(options) {
  options.path = undefined;

  if (!options.servername && options.servername !== '') {
    options.servername = net.isIP(options.host) ? '' : options.host;
  }

  return tls.connect(options);
}

/**
 * Abort the handshake and emit an error.
 *
 * @param {WebSocket} websocket The WebSocket instance
 * @param {(http.ClientRequest|net.Socket|tls.Socket)} stream The request to
 *     abort or the socket to destroy
 * @param {String} message The error message
 * @private
 */
function abortHandshake(websocket, stream, message) {
  websocket._readyState = WebSocket.CLOSING;

  const err = new Error(message);
  Error.captureStackTrace(err, abortHandshake);

  if (stream.setHeader) {
    stream.abort();

    if (stream.socket && !stream.socket.destroyed) {
      //
      // On Node.js >= 14.3.0 `request.abort()` does not destroy the socket if
      // called after the request completed. See
      // https://github.com/websockets/ws/issues/1869.
      //
      stream.socket.destroy();
    }

    stream.once('abort', websocket.emitClose.bind(websocket));
    websocket.emit('error', err);
  } else {
    stream.destroy(err);
    stream.once('error', websocket.emit.bind(websocket, 'error'));
    stream.once('close', websocket.emitClose.bind(websocket));
  }
}

/**
 * Handle cases where the `ping()`, `pong()`, or `send()` methods are called
 * when the `readyState` attribute is `CLOSING` or `CLOSED`.
 *
 * @param {WebSocket} websocket The WebSocket instance
 * @param {*} [data] The data to send
 * @param {Function} [cb] Callback
 * @private
 */
function sendAfterClose(websocket, data, cb) {
  if (data) {
    const length = toBuffer(data).length;

    //
    // The `_bufferedAmount` property is used only when the peer is a client and
    // the opening handshake fails. Under these circumstances, in fact, the
    // `setSocket()` method is not called, so the `_socket` and `_sender`
    // properties are set to `null`.
    //
    if (websocket._socket) websocket._sender._bufferedBytes += length;
    else websocket._bufferedAmount += length;
  }

  if (cb) {
    const err = new Error(
      `WebSocket is not open: readyState ${websocket.readyState} ` +
        `(${readyStates[websocket.readyState]})`
    );
    cb(err);
  }
}

/**
 * The listener of the `Receiver` `'conclude'` event.
 *
 * @param {Number} code The status code
 * @param {String} reason The reason for closing
 * @private
 */
function receiverOnConclude(code, reason) {
  const websocket = this[kWebSocket];

  websocket._closeFrameReceived = true;
  websocket._closeMessage = reason;
  websocket._closeCode = code;

  if (websocket._socket[kWebSocket] === undefined) return;

  websocket._socket.removeListener('data', socketOnData);
  process.nextTick(resume, websocket._socket);

  if (code === 1005) websocket.close();
  else websocket.close(code, reason);
}

/**
 * The listener of the `Receiver` `'drain'` event.
 *
 * @private
 */
function receiverOnDrain() {
  this[kWebSocket]._socket.resume();
}

/**
 * The listener of the `Receiver` `'error'` event.
 *
 * @param {(RangeError|Error)} err The emitted error
 * @private
 */
function receiverOnError(err) {
  const websocket = this[kWebSocket];

  if (websocket._socket[kWebSocket] !== undefined) {
    websocket._socket.removeListener('data', socketOnData);

    //
    // On Node.js < 14.0.0 the `'error'` event is emitted synchronously. See
    // https://github.com/websockets/ws/issues/1940.
    //
    process.nextTick(resume, websocket._socket);

    websocket.close(err[kStatusCode]);
  }

  websocket.emit('error', err);
}

/**
 * The listener of the `Receiver` `'finish'` event.
 *
 * @private
 */
function receiverOnFinish() {
  this[kWebSocket].emitClose();
}

/**
 * The listener of the `Receiver` `'message'` event.
 *
 * @param {(String|Buffer|ArrayBuffer|Buffer[])} data The message
 * @private
 */
function receiverOnMessage(data) {
  this[kWebSocket].emit('message', data);
}

/**
 * The listener of the `Receiver` `'ping'` event.
 *
 * @param {Buffer} data The data included in the ping frame
 * @private
 */
function receiverOnPing(data) {
  const websocket = this[kWebSocket];

  websocket.pong(data, !websocket._isServer, NOOP);
  websocket.emit('ping', data);
}

/**
 * The listener of the `Receiver` `'pong'` event.
 *
 * @param {Buffer} data The data included in the pong frame
 * @private
 */
function receiverOnPong(data) {
  this[kWebSocket].emit('pong', data);
}

/**
 * Resume a readable stream
 *
 * @param {Readable} stream The readable stream
 * @private
 */
function resume(stream) {
  stream.resume();
}

/**
 * The listener of the `net.Socket` `'close'` event.
 *
 * @private
 */
function socketOnClose() {
  const websocket = this[kWebSocket];

  this.removeListener('close', socketOnClose);
  this.removeListener('data', socketOnData);
  this.removeListener('end', socketOnEnd);

  websocket._readyState = WebSocket.CLOSING;

  let chunk;

  //
  // The close frame might not have been received or the `'end'` event emitted,
  // for example, if the socket was destroyed due to an error. Ensure that the
  // `receiver` stream is closed after writing any remaining buffered data to
  // it. If the readable side of the socket is in flowing mode then there is no
  // buffered data as everything has been already written and `readable.read()`
  // will return `null`. If instead, the socket is paused, any possible buffered
  // data will be read as a single chunk.
  //
  if (
    !this._readableState.endEmitted &&
    !websocket._closeFrameReceived &&
    !websocket._receiver._writableState.errorEmitted &&
    (chunk = websocket._socket.read()) !== null
  ) {
    websocket._receiver.write(chunk);
  }

  websocket._receiver.end();

  this[kWebSocket] = undefined;

  clearTimeout(websocket._closeTimer);

  if (
    websocket._receiver._writableState.finished ||
    websocket._receiver._writableState.errorEmitted
  ) {
    websocket.emitClose();
  } else {
    websocket._receiver.on('error', receiverOnFinish);
    websocket._receiver.on('finish', receiverOnFinish);
  }
}

/**
 * The listener of the `net.Socket` `'data'` event.
 *
 * @param {Buffer} chunk A chunk of data
 * @private
 */
function socketOnData(chunk) {
  if (!this[kWebSocket]._receiver.write(chunk)) {
    this.pause();
  }
}

/**
 * The listener of the `net.Socket` `'end'` event.
 *
 * @private
 */
function socketOnEnd() {
  const websocket = this[kWebSocket];

  websocket._readyState = WebSocket.CLOSING;
  websocket._receiver.end();
  this.end();
}

/**
 * The listener of the `net.Socket` `'error'` event.
 *
 * @private
 */
function socketOnError() {
  const websocket = this[kWebSocket];

  this.removeListener('error', socketOnError);
  this.on('error', NOOP);

  if (websocket) {
    websocket._readyState = WebSocket.CLOSING;
    this.destroy();
  }
}


ws

description: Simple to use, blazing fast and thoroughly tested websocket client and server for Node.js

keywords: HyBi Push RFC-6455 WebSocket WebSockets real-time

repository: websockets/ws

author: Einar Otto Stangvik <einaros@gmail.com> (http://2x.io)

license: MIT

test: nyc --reporter=lcov --reporter=text mocha --throw-deprecation test/*.test.js

lint: eslint --ignore-path .gitignore . && prettier --check --ignore-path .gitignore "**/*.{json,md,yaml,yml}"


code:
# Validate XML Names and Qualified Names

This package simply tells you whether or not a string matches the [`Name`](http://www.w3.org/TR/xml/#NT-Name) or [`QName`](http://www.w3.org/TR/xml-names/#NT-QName) productions in the XML Namespaces specification. We use it for implementing the [validate](https://dom.spec.whatwg.org/#validate) algorithm in jsdom, but you can use it for whatever you want.

## Usage

This package's main module exports two functions, `name()` and `qname()`. Both take a string and return a boolean indicating whether or not the string matches the relevant production.

```js
"use strict":
const xnv = require("xml-name-validator");

// Will return true
xnv.name("x");
xnv.name(":");
xnv.name("a:0");
xnv.name("a:b:c");

// Will return false
xnv.name("\\");
xnv.name("'");
xnv.name("0");
xnv.name("a!");

// Will return true
xnv.qname("x");
xnv.qname("a0");
xnv.qname("a:b");

// Will return false
xnv.qname(":a");
xnv.qname(":b");
xnv.qname("a:b:c");
xnv.qname("a:0");
```


xml-name-validator

description: Validates whether a string matches the production for an XML name or qualified name

keywords: xml name qname

author: Domenic Denicola <d@domenic.me> (https://domenic.me/)

repository: jsdom/xml-name-validator

test: mocha

lint: eslint .


code:
# xtend

[![browser support][3]][4]

[![locked](http://badges.github.io/stability-badges/dist/locked.svg)](http://github.com/badges/stability-badges)

Extend like a boss

xtend is a basic utility library which allows you to extend an object by appending all of the properties from each object in a list. When there are identical properties, the right-most property takes precedence.

## Examples

```js
var extend = require("xtend")

// extend returns a new object. Does not mutate arguments
var combination = extend({
    a: "a",
    b: "c"
}, {
    b: "b"
})
// { a: "a", b: "b" }
```

## Stability status: Locked

## MIT Licensed

  [3]: http://ci.testling.com/Raynos/xtend.png
  [4]: http://ci.testling.com/Raynos/xtend


code:
module.exports = extend

var hasOwnProperty = Object.prototype.hasOwnProperty;

function extend() {
    var target = {}

    for (var i = 0; i < arguments.length; i++) {
        var source = arguments[i]

        for (var key in source) {
            if (hasOwnProperty.call(source, key)) {
                target[key] = source[key]
            }
        }
    }

    return target
}


code:
module.exports = extend

var hasOwnProperty = Object.prototype.hasOwnProperty;

function extend(target) {
    for (var i = 1; i < arguments.length; i++) {
        var source = arguments[i]

        for (var key in source) {
            if (hasOwnProperty.call(source, key)) {
                target[key] = source[key]
            }
        }
    }

    return target
}


xtend

description: extend like a boss

keywords: extend merge options opts object array

author: Raynos <raynos2@gmail.com>

main: immutable

test: node test


code:
var test = require("tape")
var extend = require("./")
var mutableExtend = require("./mutable")

test("merge", function(assert) {
    var a = { a: "foo" }
    var b = { b: "bar" }

    assert.deepEqual(extend(a, b), { a: "foo", b: "bar" })
    assert.end()
})

test("replace", function(assert) {
    var a = { a: "foo" }
    var b = { a: "bar" }

    assert.deepEqual(extend(a, b), { a: "bar" })
    assert.end()
})

test("undefined", function(assert) {
    var a = { a: undefined }
    var b = { b: "foo" }

    assert.deepEqual(extend(a, b), { a: undefined, b: "foo" })
    assert.deepEqual(extend(b, a), { a: undefined, b: "foo" })
    assert.end()
})

test("handle 0", function(assert) {
    var a = { a: "default" }
    var b = { a: 0 }

    assert.deepEqual(extend(a, b), { a: 0 })
    assert.deepEqual(extend(b, a), { a: "default" })
    assert.end()
})

test("is immutable", function (assert) {
    var record = {}

    extend(record, { foo: "bar" })
    assert.equal(record.foo, undefined)
    assert.end()
})

test("null as argument", function (assert) {
    var a = { foo: "bar" }
    var b = null
    var c = void 0

    assert.deepEqual(extend(b, a, c), { foo: "bar" })
    assert.end()
})

test("mutable", function (assert) {
    var a = { foo: "bar" }

    mutableExtend(a, { bar: "baz" })

    assert.equal(a.bar, "baz")
    assert.end()
})

test("null prototype", function(assert) {
    var a = { a: "foo" }
    var b = Object.create(null)
    b.b = "bar";

    assert.deepEqual(extend(a, b), { a: "foo", b: "bar" })
    assert.end()
})

test("null prototype mutable", function (assert) {
    var a = { foo: "bar" }
    var b = Object.create(null)
    b.bar = "baz";

    mutableExtend(a, b)

    assert.equal(a.bar, "baz")
    assert.end()
})

test("prototype pollution", function (assert) {
    var a = {}
    var maliciousPayload = '{"__proto__":{"oops":"It works!"}}'

    assert.strictEqual(a.oops, undefined)
    extend({}, maliciousPayload)
    assert.strictEqual(a.oops, undefined)
    assert.end()
})

test("prototype pollution mutable", function (assert) {
    var a = {}
    var maliciousPayload = '{"__proto__":{"oops":"It works!"}}'

    assert.strictEqual(a.oops, undefined)
    mutableExtend({}, maliciousPayload)
    assert.strictEqual(a.oops, undefined)
    assert.end()
})


code:
# Change Log

All notable changes to this project will be documented in this file. See [standard-version](https://github.com/conventional-changelog/standard-version) for commit guidelines.

### [5.0.8](https://www.github.com/yargs/y18n/compare/v5.0.7...v5.0.8) (2021-04-07)

### Bug Fixes

* **deno:** force modern release for Deno ([b1c215a](https://www.github.com/yargs/y18n/commit/b1c215aed714bee5830e76de3e335504dc2c4dab))

### [5.0.7](https://www.github.com/yargs/y18n/compare/v5.0.6...v5.0.7) (2021-04-07)

### Bug Fixes

* **deno:** force release for deno ([#121](https://www.github.com/yargs/y18n/issues/121)) ([d3f2560](https://www.github.com/yargs/y18n/commit/d3f2560e6cedf2bfa2352e9eec044da53f9a06b2))

### [5.0.6](https://www.github.com/yargs/y18n/compare/v5.0.5...v5.0.6) (2021-04-05)

### Bug Fixes

* **webpack:** skip readFileSync if not defined ([#117](https://www.github.com/yargs/y18n/issues/117)) ([6966fa9](https://www.github.com/yargs/y18n/commit/6966fa91d2881cc6a6c531e836099e01f4da1616))

### [5.0.5](https://www.github.com/yargs/y18n/compare/v5.0.4...v5.0.5) (2020-10-25)

### Bug Fixes

* address prototype pollution issue ([#108](https://www.github.com/yargs/y18n/issues/108)) ([a9ac604](https://www.github.com/yargs/y18n/commit/a9ac604abf756dec9687be3843e2c93bfe581f25))

### [5.0.4](https://www.github.com/yargs/y18n/compare/v5.0.3...v5.0.4) (2020-10-16)

### Bug Fixes

* **exports:** node 13.0 and 13.1 require the dotted object form _with_ a string fallback ([#105](https://www.github.com/yargs/y18n/issues/105)) ([4f85d80](https://www.github.com/yargs/y18n/commit/4f85d80dbaae6d2c7899ae394f7ad97805df4886))

### [5.0.3](https://www.github.com/yargs/y18n/compare/v5.0.2...v5.0.3) (2020-10-16)

### Bug Fixes

* **exports:** node 13.0-13.6 require a string fallback ([#103](https://www.github.com/yargs/y18n/issues/103)) ([e39921e](https://www.github.com/yargs/y18n/commit/e39921e1017f88f5d8ea97ddea854ffe92d68e74))

### [5.0.2](https://www.github.com/yargs/y18n/compare/v5.0.1...v5.0.2) (2020-10-01)

### Bug Fixes

* **deno:** update types for deno ^1.4.0 ([#100](https://www.github.com/yargs/y18n/issues/100)) ([3834d9a](https://www.github.com/yargs/y18n/commit/3834d9ab1332f2937c935ada5e76623290efae81))

### [5.0.1](https://www.github.com/yargs/y18n/compare/v5.0.0...v5.0.1) (2020-09-05)

### Bug Fixes

* main had old index path ([#98](https://www.github.com/yargs/y18n/issues/98)) ([124f7b0](https://www.github.com/yargs/y18n/commit/124f7b047ba9596bdbdf64459988304e77f3de1b))

## [5.0.0](https://www.github.com/yargs/y18n/compare/v4.0.0...v5.0.0) (2020-09-05)

### ⚠ BREAKING CHANGES

* exports maps are now used, which modifies import behavior.
* drops Node 6 and 4. begin following Node.js LTS schedule (#89)

### Features

* add support for ESM and Deno [#95](https://www.github.com/yargs/y18n/issues/95)) ([4d7ae94](https://www.github.com/yargs/y18n/commit/4d7ae94bcb42e84164e2180366474b1cd321ed94))

### Build System

* drops Node 6 and 4. begin following Node.js LTS schedule ([#89](https://www.github.com/yargs/y18n/issues/89)) ([3cc0c28](https://www.github.com/yargs/y18n/commit/3cc0c287240727b84eaf1927f903612ec80f5e43))

### 4.0.1 (2020-10-25)

### Bug Fixes

* address prototype pollution issue ([#108](https://www.github.com/yargs/y18n/issues/108)) ([a9ac604](https://www.github.com/yargs/y18n/commit/7de58ca0d315990cdb38234e97fc66254cdbcd71))

## [4.0.0](https://github.com/yargs/y18n/compare/v3.2.1...v4.0.0) (2017-10-10)

### Bug Fixes

* allow support for falsy values like 0 in tagged literal ([#45](https://github.com/yargs/y18n/issues/45)) ([c926123](https://github.com/yargs/y18n/commit/c926123))

### Features

* **__:** added tagged template literal support ([#44](https://github.com/yargs/y18n/issues/44)) ([0598daf](https://github.com/yargs/y18n/commit/0598daf))

### BREAKING CHANGES

* **__:** dropping Node 0.10/Node 0.12 support


code:
# y18n

[![NPM version][npm-image]][npm-url]
[![js-standard-style][standard-image]][standard-url]
[![Conventional Commits](https://img.shields.io/badge/Conventional%20Commits-1.0.0-yellow.svg)](https://conventionalcommits.org)

The bare-bones internationalization library used by yargs.

Inspired by [i18n](https://www.npmjs.com/package/i18n).

## Examples

_simple string translation:_

```js
const __ = require('y18n')().__;

console.log(__('my awesome string %s', 'foo'));
```

output:

`my awesome string foo`

_using tagged template literals_

```js
const __ = require('y18n')().__;

const str = 'foo';

console.log(__`my awesome string ${str}`);
```

output:

`my awesome string foo`

_pluralization support:_

```js
const __n = require('y18n')().__n;

console.log(__n('one fish %s', '%d fishes %s', 2, 'foo'));
```

output:

`2 fishes foo`

## Deno Example

As of `v5` `y18n` supports [Deno](https://github.com/denoland/deno):

```typescript
import y18n from "https://deno.land/x/y18n/deno.ts";

const __ = y18n({
  locale: 'pirate',
  directory: './test/locales'
}).__

console.info(__`Hi, ${'Ben'} ${'Coe'}!`)
```

You will need to run with `--allow-read` to load alternative locales.

## JSON Language Files

The JSON language files should be stored in a `./locales` folder.
File names correspond to locales, e.g., `en.json`, `pirate.json`.

When strings are observed for the first time they will be
added to the JSON file corresponding to the current locale.

## Methods

### require('y18n')(config)

Create an instance of y18n with the config provided, options include:

* `directory`: the locale directory, default `./locales`.
* `updateFiles`: should newly observed strings be updated in file, default `true`.
* `locale`: what locale should be used.
* `fallbackToLanguage`: should fallback to a language-only file (e.g. `en.json`)
  be allowed if a file matching the locale does not exist (e.g. `en_US.json`),
  default `true`.

### y18n.\_\_(str, arg, arg, arg)

Print a localized string, `%s` will be replaced with `arg`s.

This function can also be used as a tag for a template literal. You can use it
like this: <code>__`hello ${'world'}`</code>. This will be equivalent to
`__('hello %s', 'world')`.

### y18n.\_\_n(singularString, pluralString, count, arg, arg, arg)

Print a localized string with appropriate pluralization. If `%d` is provided
in the string, the `count` will replace this placeholder.

### y18n.setLocale(str)

Set the current locale being used.

### y18n.getLocale()

What locale is currently being used?

### y18n.updateLocale(obj)

Update the current locale with the key value pairs in `obj`.

## Supported Node.js Versions

Libraries in this ecosystem make a best effort to track
[Node.js' release schedule](https://nodejs.org/en/about/releases/). Here's [a
post on why we think this is important](https://medium.com/the-node-js-collection/maintainers-should-consider-following-node-js-release-schedule-ab08ed4de71a).

## License

ISC

[npm-url]: https://npmjs.org/package/y18n
[npm-image]: https://img.shields.io/npm/v/y18n.svg
[standard-image]: https://img.shields.io/badge/code%20style-standard-brightgreen.svg
[standard-url]: https://github.com/feross/standard


code:
'use strict';

var fs = require('fs');
var util = require('util');
var path = require('path');

let shim;
class Y18N {
    constructor(opts) {
        // configurable options.
        opts = opts || {};
        this.directory = opts.directory || './locales';
        this.updateFiles = typeof opts.updateFiles === 'boolean' ? opts.updateFiles : true;
        this.locale = opts.locale || 'en';
        this.fallbackToLanguage = typeof opts.fallbackToLanguage === 'boolean' ? opts.fallbackToLanguage : true;
        // internal stuff.
        this.cache = Object.create(null);
        this.writeQueue = [];
    }
    __(...args) {
        if (typeof arguments[0] !== 'string') {
            return this._taggedLiteral(arguments[0], ...arguments);
        }
        const str = args.shift();
        let cb = function () { }; // start with noop.
        if (typeof args[args.length - 1] === 'function')
            cb = args.pop();
        cb = cb || function () { }; // noop.
        if (!this.cache[this.locale])
            this._readLocaleFile();
        // we've observed a new string, update the language file.
        if (!this.cache[this.locale][str] && this.updateFiles) {
            this.cache[this.locale][str] = str;
            // include the current directory and locale,
            // since these values could change before the
            // write is performed.
            this._enqueueWrite({
                directory: this.directory,
                locale: this.locale,
                cb
            });
        }
        else {
            cb();
        }
        return shim.format.apply(shim.format, [this.cache[this.locale][str] || str].concat(args));
    }
    __n() {
        const args = Array.prototype.slice.call(arguments);
        const singular = args.shift();
        const plural = args.shift();
        const quantity = args.shift();
        let cb = function () { }; // start with noop.
        if (typeof args[args.length - 1] === 'function')
            cb = args.pop();
        if (!this.cache[this.locale])
            this._readLocaleFile();
        let str = quantity === 1 ? singular : plural;
        if (this.cache[this.locale][singular]) {
            const entry = this.cache[this.locale][singular];
            str = entry[quantity === 1 ? 'one' : 'other'];
        }
        // we've observed a new string, update the language file.
        if (!this.cache[this.locale][singular] && this.updateFiles) {
            this.cache[this.locale][singular] = {
                one: singular,
                other: plural
            };
            // include the current directory and locale,
            // since these values could change before the
            // write is performed.
            this._enqueueWrite({
                directory: this.directory,
                locale: this.locale,
                cb
            });
        }
        else {
            cb();
        }
        // if a %d placeholder is provided, add quantity
        // to the arguments expanded by util.format.
        const values = [str];
        if (~str.indexOf('%d'))
            values.push(quantity);
        return shim.format.apply(shim.format, values.concat(args));
    }
    setLocale(locale) {
        this.locale = locale;
    }
    getLocale() {
        return this.locale;
    }
    updateLocale(obj) {
        if (!this.cache[this.locale])
            this._readLocaleFile();
        for (const key in obj) {
            if (Object.prototype.hasOwnProperty.call(obj, key)) {
                this.cache[this.locale][key] = obj[key];
            }
        }
    }
    _taggedLiteral(parts, ...args) {
        let str = '';
        parts.forEach(function (part, i) {
            const arg = args[i + 1];
            str += part;
            if (typeof arg !== 'undefined') {
                str += '%s';
            }
        });
        return this.__.apply(this, [str].concat([].slice.call(args, 1)));
    }
    _enqueueWrite(work) {
        this.writeQueue.push(work);
        if (this.writeQueue.length === 1)
            this._processWriteQueue();
    }
    _processWriteQueue() {
        const _this = this;
        const work = this.writeQueue[0];
        // destructure the enqueued work.
        const directory = work.directory;
        const locale = work.locale;
        const cb = work.cb;
        const languageFile = this._resolveLocaleFile(directory, locale);
        const serializedLocale = JSON.stringify(this.cache[locale], null, 2);
        shim.fs.writeFile(languageFile, serializedLocale, 'utf-8', function (err) {
            _this.writeQueue.shift();
            if (_this.writeQueue.length > 0)
                _this._processWriteQueue();
            cb(err);
        });
    }
    _readLocaleFile() {
        let localeLookup = {};
        const languageFile = this._resolveLocaleFile(this.directory, this.locale);
        try {
            // When using a bundler such as webpack, readFileSync may not be defined:
            if (shim.fs.readFileSync) {
                localeLookup = JSON.parse(shim.fs.readFileSync(languageFile, 'utf-8'));
            }
        }
        catch (err) {
            if (err instanceof SyntaxError) {
                err.message = 'syntax error in ' + languageFile;
            }
            if (err.code === 'ENOENT')
                localeLookup = {};
            else
                throw err;
        }
        this.cache[this.locale] = localeLookup;
    }
    _resolveLocaleFile(directory, locale) {
        let file = shim.resolve(directory, './', locale + '.json');
        if (this.fallbackToLanguage && !this._fileExistsSync(file) && ~locale.lastIndexOf('_')) {
            // attempt fallback to language only
            const languageFile = shim.resolve(directory, './', locale.split('_')[0] + '.json');
            if (this._fileExistsSync(languageFile))
                file = languageFile;
        }
        return file;
    }
    _fileExistsSync(file) {
        return shim.exists(file);
    }
}
function y18n$1(opts, _shim) {
    shim = _shim;
    const y18n = new Y18N(opts);
    return {
        __: y18n.__.bind(y18n),
        __n: y18n.__n.bind(y18n),
        setLocale: y18n.setLocale.bind(y18n),
        getLocale: y18n.getLocale.bind(y18n),
        updateLocale: y18n.updateLocale.bind(y18n),
        locale: y18n.locale
    };
}

var nodePlatformShim = {
    fs: {
        readFileSync: fs.readFileSync,
        writeFile: fs.writeFile
    },
    format: util.format,
    resolve: path.resolve,
    exists: (file) => {
        try {
            return fs.statSync(file).isFile();
        }
        catch (err) {
            return false;
        }
    }
};

const y18n = (opts) => {
    return y18n$1(opts, nodePlatformShim);
};

module.exports = y18n;


code:
import { y18n as _y18n } from './index.js';
import nodePlatformShim from './platform-shims/node.js';
const y18n = (opts) => {
    return _y18n(opts, nodePlatformShim);
};
export default y18n;


code:
let shim;
class Y18N {
    constructor(opts) {
        // configurable options.
        opts = opts || {};
        this.directory = opts.directory || './locales';
        this.updateFiles = typeof opts.updateFiles === 'boolean' ? opts.updateFiles : true;
        this.locale = opts.locale || 'en';
        this.fallbackToLanguage = typeof opts.fallbackToLanguage === 'boolean' ? opts.fallbackToLanguage : true;
        // internal stuff.
        this.cache = Object.create(null);
        this.writeQueue = [];
    }
    __(...args) {
        if (typeof arguments[0] !== 'string') {
            return this._taggedLiteral(arguments[0], ...arguments);
        }
        const str = args.shift();
        let cb = function () { }; // start with noop.
        if (typeof args[args.length - 1] === 'function')
            cb = args.pop();
        cb = cb || function () { }; // noop.
        if (!this.cache[this.locale])
            this._readLocaleFile();
        // we've observed a new string, update the language file.
        if (!this.cache[this.locale][str] && this.updateFiles) {
            this.cache[this.locale][str] = str;
            // include the current directory and locale,
            // since these values could change before the
            // write is performed.
            this._enqueueWrite({
                directory: this.directory,
                locale: this.locale,
                cb
            });
        }
        else {
            cb();
        }
        return shim.format.apply(shim.format, [this.cache[this.locale][str] || str].concat(args));
    }
    __n() {
        const args = Array.prototype.slice.call(arguments);
        const singular = args.shift();
        const plural = args.shift();
        const quantity = args.shift();
        let cb = function () { }; // start with noop.
        if (typeof args[args.length - 1] === 'function')
            cb = args.pop();
        if (!this.cache[this.locale])
            this._readLocaleFile();
        let str = quantity === 1 ? singular : plural;
        if (this.cache[this.locale][singular]) {
            const entry = this.cache[this.locale][singular];
            str = entry[quantity === 1 ? 'one' : 'other'];
        }
        // we've observed a new string, update the language file.
        if (!this.cache[this.locale][singular] && this.updateFiles) {
            this.cache[this.locale][singular] = {
                one: singular,
                other: plural
            };
            // include the current directory and locale,
            // since these values could change before the
            // write is performed.
            this._enqueueWrite({
                directory: this.directory,
                locale: this.locale,
                cb
            });
        }
        else {
            cb();
        }
        // if a %d placeholder is provided, add quantity
        // to the arguments expanded by util.format.
        const values = [str];
        if (~str.indexOf('%d'))
            values.push(quantity);
        return shim.format.apply(shim.format, values.concat(args));
    }
    setLocale(locale) {
        this.locale = locale;
    }
    getLocale() {
        return this.locale;
    }
    updateLocale(obj) {
        if (!this.cache[this.locale])
            this._readLocaleFile();
        for (const key in obj) {
            if (Object.prototype.hasOwnProperty.call(obj, key)) {
                this.cache[this.locale][key] = obj[key];
            }
        }
    }
    _taggedLiteral(parts, ...args) {
        let str = '';
        parts.forEach(function (part, i) {
            const arg = args[i + 1];
            str += part;
            if (typeof arg !== 'undefined') {
                str += '%s';
            }
        });
        return this.__.apply(this, [str].concat([].slice.call(args, 1)));
    }
    _enqueueWrite(work) {
        this.writeQueue.push(work);
        if (this.writeQueue.length === 1)
            this._processWriteQueue();
    }
    _processWriteQueue() {
        const _this = this;
        const work = this.writeQueue[0];
        // destructure the enqueued work.
        const directory = work.directory;
        const locale = work.locale;
        const cb = work.cb;
        const languageFile = this._resolveLocaleFile(directory, locale);
        const serializedLocale = JSON.stringify(this.cache[locale], null, 2);
        shim.fs.writeFile(languageFile, serializedLocale, 'utf-8', function (err) {
            _this.writeQueue.shift();
            if (_this.writeQueue.length > 0)
                _this._processWriteQueue();
            cb(err);
        });
    }
    _readLocaleFile() {
        let localeLookup = {};
        const languageFile = this._resolveLocaleFile(this.directory, this.locale);
        try {
            // When using a bundler such as webpack, readFileSync may not be defined:
            if (shim.fs.readFileSync) {
                localeLookup = JSON.parse(shim.fs.readFileSync(languageFile, 'utf-8'));
            }
        }
        catch (err) {
            if (err instanceof SyntaxError) {
                err.message = 'syntax error in ' + languageFile;
            }
            if (err.code === 'ENOENT')
                localeLookup = {};
            else
                throw err;
        }
        this.cache[this.locale] = localeLookup;
    }
    _resolveLocaleFile(directory, locale) {
        let file = shim.resolve(directory, './', locale + '.json');
        if (this.fallbackToLanguage && !this._fileExistsSync(file) && ~locale.lastIndexOf('_')) {
            // attempt fallback to language only
            const languageFile = shim.resolve(directory, './', locale.split('_')[0] + '.json');
            if (this._fileExistsSync(languageFile))
                file = languageFile;
        }
        return file;
    }
    _fileExistsSync(file) {
        return shim.exists(file);
    }
}
export function y18n(opts, _shim) {
    shim = _shim;
    const y18n = new Y18N(opts);
    return {
        __: y18n.__.bind(y18n),
        __n: y18n.__n.bind(y18n),
        setLocale: y18n.setLocale.bind(y18n),
        getLocale: y18n.getLocale.bind(y18n),
        updateLocale: y18n.updateLocale.bind(y18n),
        locale: y18n.locale
    };
}


code:
import { readFileSync, statSync, writeFile } from 'fs';
import { format } from 'util';
import { resolve } from 'path';
export default {
    fs: {
        readFileSync,
        writeFile
    },
    format,
    resolve,
    exists: (file) => {
        try {
            return statSync(file).isFile();
        }
        catch (err) {
            return false;
        }
    }
};


code:
import shim from './build/lib/platform-shims/node.js'
import { y18n as _y18n } from './build/lib/index.js'

const y18n = (opts) => {
  return _y18n(opts, shim)
}

export default y18n


description: the bare-bones internationalization library used by yargs

type: module

keywords: i18n internationalization yargs

license: ISC

author: Ben Coe <bencoe@gmail.com>

check: standardx **/*.ts **/*.cjs **/*.mjs

fix: standardx --fix **/*.ts **/*.cjs **/*.mjs

pretest: rimraf build && tsc -p tsconfig.test.json && cross-env NODE_ENV=test npm run build:cjs

test: c8 --reporter=text --reporter=html mocha test/*.cjs

test:esm: c8 --reporter=text --reporter=html mocha test/esm/*.mjs

posttest: npm run check

coverage: c8 report --check-coverage

precompile: rimraf build

compile: tsc

postcompile: npm run build:cjs

build:cjs: rollup -c

prepare: npm run compile


code:
# yallist

Yet Another Linked List

There are many doubly-linked list implementations like it, but this
one is mine.

For when an array would be too big, and a Map can't be iterated in
reverse order.

[![Build Status](https://travis-ci.org/isaacs/yallist.svg?branch=master)](https://travis-ci.org/isaacs/yallist) [![Coverage Status](https://coveralls.io/repos/isaacs/yallist/badge.svg?service=github)](https://coveralls.io/github/isaacs/yallist)

## basic usage

```javascript
var yallist = require('yallist')
var myList = yallist.create([1, 2, 3])
myList.push('foo')
myList.unshift('bar')
// of course pop() and shift() are there, too
console.log(myList.toArray()) // ['bar', 1, 2, 3, 'foo']
myList.forEach(function (k) {
  // walk the list head to tail
})
myList.forEachReverse(function (k, index, list) {
  // walk the list tail to head
})
var myDoubledList = myList.map(function (k) {
  return k + k
})
// now myDoubledList contains ['barbar', 2, 4, 6, 'foofoo']
// mapReverse is also a thing
var myDoubledListReverse = myList.mapReverse(function (k) {
  return k + k
}) // ['foofoo', 6, 4, 2, 'barbar']

var reduced = myList.reduce(function (set, entry) {
  set += entry
  return set
}, 'start')
console.log(reduced) // 'startfoo123bar'
```

## api

The whole API is considered "public".

Functions with the same name as an Array method work more or less the
same way.

There's reverse versions of most things because that's the point.

### Yallist

Default export, the class that holds and manages a list.

Call it with either a forEach-able (like an array) or a set of
arguments, to initialize the list.

The Array-ish methods all act like you'd expect.  No magic length,
though, so if you change that it won't automatically prune or add
empty spots.

### Yallist.create(..)

Alias for Yallist function.  Some people like factories.

#### yallist.head

The first node in the list

#### yallist.tail

The last node in the list

#### yallist.length

The number of nodes in the list.  (Change this at your peril.  It is
not magic like Array length.)

#### yallist.toArray()

Convert the list to an array.

#### yallist.forEach(fn, [thisp])

Call a function on each item in the list.

#### yallist.forEachReverse(fn, [thisp])

Call a function on each item in the list, in reverse order.

#### yallist.get(n)

Get the data at position `n` in the list.  If you use this a lot,
probably better off just using an Array.

#### yallist.getReverse(n)

Get the data at position `n`, counting from the tail.

#### yallist.map(fn, thisp)

Create a new Yallist with the result of calling the function on each
item.

#### yallist.mapReverse(fn, thisp)

Same as `map`, but in reverse.

#### yallist.pop()

Get the data from the list tail, and remove the tail from the list.

#### yallist.push(item, ...)

Insert one or more items to the tail of the list.

#### yallist.reduce(fn, initialValue)

Like Array.reduce.

#### yallist.reduceReverse

Like Array.reduce, but in reverse.

#### yallist.reverse

Reverse the list in place.

#### yallist.shift()

Get the data from the list head, and remove the head from the list.

#### yallist.slice([from], [to])

Just like Array.slice, but returns a new Yallist.

#### yallist.sliceReverse([from], [to])

Just like yallist.slice, but the result is returned in reverse.

#### yallist.toArray()

Create an array representation of the list.

#### yallist.toArrayReverse()

Create a reversed array representation of the list.

#### yallist.unshift(item, ...)

Insert one or more items to the head of the list.

#### yallist.unshiftNode(node)

Move a Node object to the front of the list.  (That is, pull it out of
wherever it lives, and make it the new head.)

If the node belongs to a different list, then that list will remove it
first.

#### yallist.pushNode(node)

Move a Node object to the end of the list.  (That is, pull it out of
wherever it lives, and make it the new tail.)

If the node belongs to a list already, then that list will remove it
first.

#### yallist.removeNode(node)

Remove a node from the list, preserving referential integrity of head
and tail and other nodes.

Will throw an error if you try to have a list remove a node that
doesn't belong to it.

### Yallist.Node

The class that holds the data and is actually the list.

Call with `var n = new Node(value, previousNode, nextNode)`

Note that if you do direct operations on Nodes themselves, it's very
easy to get into weird states where the list is broken.  Be careful :)

#### node.next

The next node in the list.

#### node.prev

The previous node in the list.

#### node.value

The data the node contains.

#### node.list

The list to which this node belongs.  (Null if it does not belong to
any list.)


code:
'use strict'
module.exports = function (Yallist) {
  Yallist.prototype[Symbol.iterator] = function* () {
    for (let walker = this.head; walker; walker = walker.next) {
      yield walker.value
    }
  }
}


yallist

description: Yet Another Linked List

test: test

test: tap test/*.js --100

preversion: npm test

postversion: npm publish

postpublish: git push origin --all; git push origin --tags

type: git

author: Isaac Z. Schlueter <i@izs.me> (http://blog.izs.me/)


code:
'use strict'
module.exports = Yallist

Yallist.Node = Node
Yallist.create = Yallist

function Yallist (list) {
  var self = this
  if (!(self instanceof Yallist)) {
    self = new Yallist()
  }

  self.tail = null
  self.head = null
  self.length = 0

  if (list && typeof list.forEach === 'function') {
    list.forEach(function (item) {
      self.push(item)
    })
  } else if (arguments.length > 0) {
    for (var i = 0, l = arguments.length; i < l; i++) {
      self.push(arguments[i])
    }
  }

  return self
}

Yallist.prototype.removeNode = function (node) {
  if (node.list !== this) {
    throw new Error('removing node which does not belong to this list')
  }

  var next = node.next
  var prev = node.prev

  if (next) {
    next.prev = prev
  }

  if (prev) {
    prev.next = next
  }

  if (node === this.head) {
    this.head = next
  }
  if (node === this.tail) {
    this.tail = prev
  }

  node.list.length--
  node.next = null
  node.prev = null
  node.list = null

  return next
}

Yallist.prototype.unshiftNode = function (node) {
  if (node === this.head) {
    return
  }

  if (node.list) {
    node.list.removeNode(node)
  }

  var head = this.head
  node.list = this
  node.next = head
  if (head) {
    head.prev = node
  }

  this.head = node
  if (!this.tail) {
    this.tail = node
  }
  this.length++
}

Yallist.prototype.pushNode = function (node) {
  if (node === this.tail) {
    return
  }

  if (node.list) {
    node.list.removeNode(node)
  }

  var tail = this.tail
  node.list = this
  node.prev = tail
  if (tail) {
    tail.next = node
  }

  this.tail = node
  if (!this.head) {
    this.head = node
  }
  this.length++
}

Yallist.prototype.push = function () {
  for (var i = 0, l = arguments.length; i < l; i++) {
    push(this, arguments[i])
  }
  return this.length
}

Yallist.prototype.unshift = function () {
  for (var i = 0, l = arguments.length; i < l; i++) {
    unshift(this, arguments[i])
  }
  return this.length
}

Yallist.prototype.pop = function () {
  if (!this.tail) {
    return undefined
  }

  var res = this.tail.value
  this.tail = this.tail.prev
  if (this.tail) {
    this.tail.next = null
  } else {
    this.head = null
  }
  this.length--
  return res
}

Yallist.prototype.shift = function () {
  if (!this.head) {
    return undefined
  }

  var res = this.head.value
  this.head = this.head.next
  if (this.head) {
    this.head.prev = null
  } else {
    this.tail = null
  }
  this.length--
  return res
}

Yallist.prototype.forEach = function (fn, thisp) {
  thisp = thisp || this
  for (var walker = this.head, i = 0; walker !== null; i++) {
    fn.call(thisp, walker.value, i, this)
    walker = walker.next
  }
}

Yallist.prototype.forEachReverse = function (fn, thisp) {
  thisp = thisp || this
  for (var walker = this.tail, i = this.length - 1; walker !== null; i--) {
    fn.call(thisp, walker.value, i, this)
    walker = walker.prev
  }
}

Yallist.prototype.get = function (n) {
  for (var i = 0, walker = this.head; walker !== null && i < n; i++) {
    // abort out of the list early if we hit a cycle
    walker = walker.next
  }
  if (i === n && walker !== null) {
    return walker.value
  }
}

Yallist.prototype.getReverse = function (n) {
  for (var i = 0, walker = this.tail; walker !== null && i < n; i++) {
    // abort out of the list early if we hit a cycle
    walker = walker.prev
  }
  if (i === n && walker !== null) {
    return walker.value
  }
}

Yallist.prototype.map = function (fn, thisp) {
  thisp = thisp || this
  var res = new Yallist()
  for (var walker = this.head; walker !== null;) {
    res.push(fn.call(thisp, walker.value, this))
    walker = walker.next
  }
  return res
}

Yallist.prototype.mapReverse = function (fn, thisp) {
  thisp = thisp || this
  var res = new Yallist()
  for (var walker = this.tail; walker !== null;) {
    res.push(fn.call(thisp, walker.value, this))
    walker = walker.prev
  }
  return res
}

Yallist.prototype.reduce = function (fn, initial) {
  var acc
  var walker = this.head
  if (arguments.length > 1) {
    acc = initial
  } else if (this.head) {
    walker = this.head.next
    acc = this.head.value
  } else {
    throw new TypeError('Reduce of empty list with no initial value')
  }

  for (var i = 0; walker !== null; i++) {
    acc = fn(acc, walker.value, i)
    walker = walker.next
  }

  return acc
}

Yallist.prototype.reduceReverse = function (fn, initial) {
  var acc
  var walker = this.tail
  if (arguments.length > 1) {
    acc = initial
  } else if (this.tail) {
    walker = this.tail.prev
    acc = this.tail.value
  } else {
    throw new TypeError('Reduce of empty list with no initial value')
  }

  for (var i = this.length - 1; walker !== null; i--) {
    acc = fn(acc, walker.value, i)
    walker = walker.prev
  }

  return acc
}

Yallist.prototype.toArray = function () {
  var arr = new Array(this.length)
  for (var i = 0, walker = this.head; walker !== null; i++) {
    arr[i] = walker.value
    walker = walker.next
  }
  return arr
}

Yallist.prototype.toArrayReverse = function () {
  var arr = new Array(this.length)
  for (var i = 0, walker = this.tail; walker !== null; i++) {
    arr[i] = walker.value
    walker = walker.prev
  }
  return arr
}

Yallist.prototype.slice = function (from, to) {
  to = to || this.length
  if (to < 0) {
    to += this.length
  }
  from = from || 0
  if (from < 0) {
    from += this.length
  }
  var ret = new Yallist()
  if (to < from || to < 0) {
    return ret
  }
  if (from < 0) {
    from = 0
  }
  if (to > this.length) {
    to = this.length
  }
  for (var i = 0, walker = this.head; walker !== null && i < from; i++) {
    walker = walker.next
  }
  for (; walker !== null && i < to; i++, walker = walker.next) {
    ret.push(walker.value)
  }
  return ret
}

Yallist.prototype.sliceReverse = function (from, to) {
  to = to || this.length
  if (to < 0) {
    to += this.length
  }
  from = from || 0
  if (from < 0) {
    from += this.length
  }
  var ret = new Yallist()
  if (to < from || to < 0) {
    return ret
  }
  if (from < 0) {
    from = 0
  }
  if (to > this.length) {
    to = this.length
  }
  for (var i = this.length, walker = this.tail; walker !== null && i > to; i--) {
    walker = walker.prev
  }
  for (; walker !== null && i > from; i--, walker = walker.prev) {
    ret.push(walker.value)
  }
  return ret
}

Yallist.prototype.splice = function (start, deleteCount /*, ...nodes */) {
  if (start > this.length) {
    start = this.length - 1
  }
  if (start < 0) {
    start = this.length + start;
  }

  for (var i = 0, walker = this.head; walker !== null && i < start; i++) {
    walker = walker.next
  }

  var ret = []
  for (var i = 0; walker && i < deleteCount; i++) {
    ret.push(walker.value)
    walker = this.removeNode(walker)
  }
  if (walker === null) {
    walker = this.tail
  }

  if (walker !== this.head && walker !== this.tail) {
    walker = walker.prev
  }

  for (var i = 2; i < arguments.length; i++) {
    walker = insert(this, walker, arguments[i])
  }
  return ret;
}

Yallist.prototype.reverse = function () {
  var head = this.head
  var tail = this.tail
  for (var walker = head; walker !== null; walker = walker.prev) {
    var p = walker.prev
    walker.prev = walker.next
    walker.next = p
  }
  this.head = tail
  this.tail = head
  return this
}

function insert (self, node, value) {
  var inserted = node === self.head ?
    new Node(value, null, node, self) :
    new Node(value, node, node.next, self)

  if (inserted.next === null) {
    self.tail = inserted
  }
  if (inserted.prev === null) {
    self.head = inserted
  }

  self.length++

  return inserted
}

function push (self, item) {
  self.tail = new Node(item, self.tail, null, self)
  if (!self.head) {
    self.head = self.tail
  }
  self.length++
}

function unshift (self, item) {
  self.head = new Node(item, null, self.head, self)
  if (!self.tail) {
    self.tail = self.head
  }
  self.length++
}

function Node (value, prev, next, list) {
  if (!(this instanceof Node)) {
    return new Node(value, prev, next, list)
  }

  this.list = list
  this.value = value

  if (prev) {
    prev.next = this
    this.prev = prev
  } else {
    this.prev = null
  }

  if (next) {
    next.prev = this
    this.next = next
  } else {
    this.next = null
  }
}

try {
  // add if support for Symbol.iterator is present
  require('./iterator.js')(Yallist)
} catch (er) {}


code:
# YAML

`yaml` is a JavaScript parser and stringifier for [YAML](http://yaml.org/), a human friendly data serialization standard. It supports both parsing and stringifying data using all versions of YAML, along with all common data schemas. As a particularly distinguishing feature, `yaml` fully supports reading and writing comments and blank lines in YAML documents.

The library is released under the ISC open source license, and the code is [available on GitHub](https://github.com/eemeli/yaml/). It has no external dependencies and runs on Node.js 6 and later, and in browsers from IE 11 upwards.

For the purposes of versioning, any changes that break any of the endpoints or APIs documented here will be considered semver-major breaking changes. Undocumented library internals may change between minor versions, and previous APIs may be deprecated (but not removed).

For more information, see the project's documentation site: [**eemeli.org/yaml/v1**](https://eemeli.org/yaml/v1/)

To install:

```sh
npm install yaml
```

**Note:** This is `yaml@1`. You may also be interested in the next version, currently available as [`yaml@next`](https://www.npmjs.com/package/yaml/v/next).

## API Overview

The API provided by `yaml` has three layers, depending on how deep you need to go: [Parse & Stringify](https://eemeli.org/yaml/v1/#parse-amp-stringify), [Documents](https://eemeli.org/yaml/#documents), and the [CST Parser](https://eemeli.org/yaml/#cst-parser). The first has the simplest API and "just works", the second gets you all the bells and whistles supported by the library along with a decent [AST](https://eemeli.org/yaml/#content-nodes), and the third is the closest to YAML source, making it fast, raw, and crude.

```js
import YAML from 'yaml'
// or
const YAML = require('yaml')
```

### Parse & Stringify

- [`YAML.parse(str, options): value`](https://eemeli.org/yaml/v1/#yaml-parse)
- [`YAML.stringify(value, options): string`](https://eemeli.org/yaml/v1/#yaml-stringify)

### YAML Documents

- [`YAML.createNode(value, wrapScalars, tag): Node`](https://eemeli.org/yaml/v1/#creating-nodes)
- [`YAML.defaultOptions`](https://eemeli.org/yaml/v1/#options)
- [`YAML.Document`](https://eemeli.org/yaml/v1/#yaml-documents)
  - [`constructor(options)`](https://eemeli.org/yaml/v1/#creating-documents)
  - [`defaults`](https://eemeli.org/yaml/v1/#options)
  - [`#anchors`](https://eemeli.org/yaml/v1/#working-with-anchors)
  - [`#contents`](https://eemeli.org/yaml/v1/#content-nodes)
  - [`#errors`](https://eemeli.org/yaml/v1/#errors)
- [`YAML.parseAllDocuments(str, options): YAML.Document[]`](https://eemeli.org/yaml/v1/#parsing-documents)
- [`YAML.parseDocument(str, options): YAML.Document`](https://eemeli.org/yaml/v1/#parsing-documents)

```js
import { Pair, YAMLMap, YAMLSeq } from 'yaml/types'
```

- [`new Pair(key, value)`](https://eemeli.org/yaml/v1/#creating-nodes)
- [`new YAMLMap()`](https://eemeli.org/yaml/v1/#creating-nodes)
- [`new YAMLSeq()`](https://eemeli.org/yaml/v1/#creating-nodes)

### CST Parser

```js
import parseCST from 'yaml/parse-cst'
```

- [`parseCST(str): CSTDocument[]`](https://eemeli.org/yaml/v1/#parsecst)
- [`YAML.parseCST(str): CSTDocument[]`](https://eemeli.org/yaml/v1/#parsecst)

## YAML.parse

```yaml
# file.yml
YAML:
  - A human-readable data serialization language
  - https://en.wikipedia.org/wiki/YAML
yaml:
  - A complete JavaScript implementation
  - https://www.npmjs.com/package/yaml
```

```js
import fs from 'fs'
import YAML from 'yaml'

YAML.parse('3.14159')
// 3.14159

YAML.parse('[ true, false, maybe, null ]\n')
// [ true, false, 'maybe', null ]

const file = fs.readFileSync('./file.yml', 'utf8')
YAML.parse(file)
// { YAML:
//   [ 'A human-readable data serialization language',
//     'https://en.wikipedia.org/wiki/YAML' ],
//   yaml:
//   [ 'A complete JavaScript implementation',
//     'https://www.npmjs.com/package/yaml' ] }
```

## YAML.stringify

```js
import YAML from 'yaml'

YAML.stringify(3.14159)
// '3.14159\n'

YAML.stringify([true, false, 'maybe', null])
// `- true
// - false
// - maybe
// - null
// `

YAML.stringify({ number: 3, plain: 'string', block: 'two\nlines\n' })
// `number: 3
// plain: string
// block: >
//   two
//
//   lines
// `
```

---

Browser testing provided by: