Step 1: Set Up Your Supabase Project
 

• Navigate to the Supabase website and log in or sign up for an account.
• Create a new project by following the on-screen instructions. Ensure you remember your API keys and project URL, as you will need them later.

Step 2: Install Required Dependencies
 

• Initialize a new Node.js project if you haven't already:

  npm init -y

• Install Supabase and other necessary libraries:

  npm install @supabase/supabase-js simple-peer

Step 3: Initialize Supabase Client
 

• Create a new JavaScript file (e.g., index.js).
• Initialize the Supabase client in your JavaScript file:

  const { createClient } = require('@supabase/supabase-js');
  const supabaseUrl = 'YOUR_SUPABASE_URL';
  const supabaseKey = 'YOUR_SUPABASE_ANON\_KEY';
  const supabase = createClient(supabaseUrl, supabaseKey);
      

Step 4: Set Up WebRTC
 

• Install Simple-Peer, which will handle the WebRTC connections:

  npm install simple-peer

• Initialize Simple-Peer instances for both the caller and receiver:

  const Peer = require('simple-peer');
  const peer = new Peer({
    initiator: location.hash === '#init',
    trickle: false
  });
  
  peer.on('signal', data => {
    // Send signal data to the other peer via Supabase
  });
      

  
  

Step 5: Implement Signaling with Supabase
 

• Create a new table in your Supabase project to store signaling data, with columns for 'id', 'type', and 'data'.
• Modify your signal event to store signals in the Supabase table:

  peer.on('signal', async (data) => {
    await supabase
      .from('signals')
      .insert([{ type: 'signal', data: JSON.stringify(data) }]);
  });
      

• Fetch and process signals in the other peer:

  supabase
    .from('signals')
    .on('INSERT', payload => {
      const signalData = JSON.parse(payload.new.data);
      peer.signal(signalData);
    })
    .subscribe();
      

Step 6: Implement Screen Sharing
 

• Add a button to your HTML to start screen sharing:

  <button id="share-screen">Share Screen</button>
      

• Use the navigator.mediaDevices.getDisplayMedia() API to capture the screen:

  document.getElementById('share-screen').addEventListener('click', async () => {
    try {
      const stream = await navigator.mediaDevices.getDisplayMedia({ video: true });
      peer.addStream(stream);
    } catch (err) {
      console.error('Error sharing the screen:', err);
    }
  });
      

• Handle the incoming stream on the receiving peer to display it:

  peer.on('stream', stream => {
    const video = document.createElement('video');
    document.body.appendChild(video);
    video.srcObject = stream;
    video.play();
  });
      

Step 7: Final Testing and Debugging
 

• Ensure both peers can connect and share screen by deploying your application and opening it in two different tabs or devices.
• Check the Supabase logs and browser console for any errors or signals not being processed correctly.
• Refine your error handling and edge cases based on the above testing.