webpack-dev-server/client/socket.js

'use strict';

var SockJS = require('sockjs-client/dist/sockjs');

var retries = 0;
var sock = null;

var socket = function initSocket(url, handlers) {
  sock = new SockJS(url);

  sock.onopen = function onopen() {
    retries = 0;
  };

  sock.onclose = function onclose() {
    if (retries === 0) {
      handlers.close();
    } // Try to reconnect.


    sock = null; // After 10 retries stop trying, to prevent logspam.

    if (retries <= 10) {
      // Exponentially increase timeout to reconnect.
      // Respectfully copied from the package `got`.
      // eslint-disable-next-line no-mixed-operators, no-restricted-properties
      var retryInMs = 1000 * Math.pow(2, retries) + Math.random() * 100;
      retries += 1;
      setTimeout(function () {
        socket(url, handlers);
      }, retryInMs);
    }
  };

  sock.onmessage = function onmessage(e) {
    // This assumes that all data sent via the websocket is JSON.
    var msg = JSON.parse(e.data);

    if (handlers[msg.type]) {
      handlers[msg.type](msg.data);
    }
  };
};

module.exports = socket;