app.py

import streamlit as st
from streamlit.components.v1 import html
import time

def main():
    st.title("HTML to Streamlit Sync Demo")
    
    # Create a session state variable for the text
    if 'text_value' not in st.session_state:
        st.session_state.text_value = "Initial text..."

    # HTML component with a textarea
    html_code = """
    <textarea id="html-textarea" style="width: 100%; height: 150px; padding: 10px; margin: 10px 0;">
    This is text in the HTML textarea.
    Try editing this text!
    </textarea>

    <script>
        // Function to get textarea content
        function getTextareaContent() {
            let content = document.getElementById('html-textarea').value;
            // Send content to Streamlit
            window.parent.postMessage({
                type: 'streamlit:setComponentValue',
                value: content
            }, '*');
        }

        // Set up timer to check for changes
        setInterval(getTextareaContent, 1000);  // Check every second
    </script>
    """

    # Column layout for side-by-side comparison
    col1, col2 = st.columns(2)

    with col1:
        st.subheader("HTML Textarea")
        # Render the HTML component
        html(html_code, height=200)

    with col2:
        st.subheader("Streamlit Textarea")
        # Streamlit textarea that shows the synced content
        synced_text = st.text_area(
            "Synced content (updates every second):",
            value=st.session_state.text_value,
            height=150,
            key="synced_textarea"
        )

    # Show the current value for debugging
    st.subheader("Current Value in Session State:")
    st.code(st.session_state.text_value)

    # Add a note about the sync behavior
    st.info("The content from the HTML textarea will sync to the Streamlit textarea every second. Try typing in the HTML textarea and watch the Streamlit textarea update!")

if __name__ == "__main__":
    main()