Simple wrapper for a Websocket connection that accepts and sends JSON data

ws.js

exports.websocket = {
  connect: function (address) {
    var ws = new WebSocket(address);
    var promise = new Promise(function (resolve, reject) {
      ws.onopen = function (e) {
        var wsObj = {
          socket: ws,
          handlers: {}
        };

        document.addEventListener("unload", function () {
          exports.websocket.close(ws);
        });

        ws.onmessage = function (msg) {
          var parsedMsg;
          try {
            parsedMsg = JSON.parse(msg.data);
          }
          catch (e) {
            console.log("Bad WS message");
          }
          var handler = wsObj.handlers[parsedMsg.type];
          if (handler) {
            handler(parsedMsg);
          }
          else {
            console.log("No handler for message type " + parsedMsg.type);
          }
        };
        resolve(wsObj);
      };
      ws.onerror = function (e) {
        reject(e);
      };
    });
    return promise;
  },

  on: function (ws, type, handler) {
    ws.handlers[type] = handler;
  },

  send: function (ws, msg) {
    ws.socket.send(JSON.stringify(msg));
  },

  close: function (ws) {
    ws.socket.close();
  }
};