file-sharing-webrtc-chunking.js

/**
 * Peer 1 (Sender)
 * Peer 2 (Receiver)
 * This example has both the peers in the same browser window.
 * In a real application, the peers would exchange their signaling data for a proper connection.
 * The signaling server part is omitted for simplicity
 */
const peer1 = new SimplePeer({ initiator: true });
const peer2 = new SimplePeer();

/**
 * Implementing the WebRTC connection between the nodes
 */

// Share the signalling data of sender with the receivers
peer1.on('signal', data => {
  peer2.signal(data);
});

// Share the signalling data of receiver with the sender
peer2.on('signal', data => {
  peer1.signal(data);
});


/**
 * Connection established, now sender can send files to other peers
 */
peer1.on('connect', () => {
  const input = document.getElementById('file-input');

  // Event listener on the file input
  input.addEventListener('change', () => {
    const file = input.files[0];
    console.log('Sending', file);

    // We convert the file from Blob to ArrayBuffer
    file.arrayBuffer()
    .then(buffer => {
      /**
       * A chunkSize (in Bytes) is set here
       * I have it set to 16KB
       */
      const chunkSize = 16 * 1024;

      // Keep chunking, and sending the chunks to the other peer
      while(buffer.byteLength) {
        const chunk = buffer.slice(0, chunkSize);
        buffer = buffer.slice(chunkSize, buffer.byteLength);
        
        // Off goes the chunk!
        peer1.send(chunk);
      }

      // End message to signal that all chunks have been sent
      peer1.send('Done!');
    });

  });
});


/**
 * Receiver receives the files
 */
const fileChunks = [];
peer2.on('data', data => {

  if (data.toString() === 'Done!') {
    // Once, all the chunks are received, combine them to form a Blob
    const file = new Blob(fileChunks);
  
    console.log('Received', file);
    // Download the received file using downloadjs
    download(file, 'test.png');
  }
  else {
    // Keep appending various file chunks 
    fileChunks.push(data);
  }

});

This is a brilliant example. Thanks.