var socket = new WebSocket("ws://localhost:3000");
socket.binaryType = "arraybuffer";

socket.onopen = function(){
  var arrayBufferMessage = stringToArrayBuffer("Test message from client");
  socket.send(arrayBufferMessage);
};

socket.onmessage = function(e){
  console.log(arrayBufferToString(e.data));
}

function stringToArrayBuffer(string){
  var buffer = new ArrayBuffer(string.length);
  var bufferView = new Uint8Array(buffer);
  for(var i = 0; i < string.length; i++){
    bufferView[i] = string.charCodeAt(i);
  }
  return bufferView;
}

function arrayBufferToString(arrayBuffer){
  return String.fromCharCode.apply(null, new Uint8Array(arrayBuffer));
}