basic-loader-amd.js

define(['module'], function (module) {
  'use strict';

  function _load(tag) {
    return function (url) {
      // This promise will be used by Promise.all to determine success or failure
      return new Promise(function (resolve, reject) {
        var element = document.createElement(tag);
        var parent = 'body';
        var attr = 'src';

        // Important success and error for the promise
        element.onload = function () {
          return resolve(url);
        };
        element.onerror = function () {
          return reject(url);
        };

        // Need to set different attributes depending on tag type
        switch (tag) {
          case 'script':
            element.async = true;
            break;
          case 'link':
            element.type = 'text/css';
            element.rel = 'stylesheet';
            attr = 'href';
            parent = 'head';
        }

        // Inject into document to kick off loading
        element[attr] = url;
        document[parent].appendChild(element);
      });
    };
  }

  module.exports = {
    css: _load('link'),
    js: _load('script'),
    img: _load('img')
  };
});