Example analysis of asynchronous script loading method with callback function in javascript_javascript skills

The example in this article describes the asynchronous script loading method with callback function in JavaScript. Share it with everyone for your reference. The specific implementation method is as follows:

var Loader = function () { }
Loader.prototype = {
  require: function (scripts, callback) {
    this.loadCount   = 0;
    this.totalRequired = scripts.length;
    this.callback    = callback;
    for (var i = 0; i < scripts.length; i++) {
      this.writeScript(scripts[i]);
    }
  },
  loaded: function (evt) {
    this.loadCount++;
    if (this.loadCount == this.totalRequired && typeof this.callback == 'function') this.callback.call();
  },
  writeScript: function (src) {
    var self = this;
    var s = document.createElement('script');
    s.type = "text/javascript";
    s.async = true;
    s.src = src;
    s.addEventListener('load', function (e) { self.loaded(e); }, false);
    var head = document.getElementsByTagName('head')[0];
    head.appendChild(s);
  }
}

Usage demonstration

var l = new Loader();
l.require([
  "example-script-1.js",
  "example-script-2.js"],
  function() {
    // Callback
    console.log('All Scripts Loaded');
  });

I hope this article will be helpful to everyone’s JavaScript programming design.