Loads the google IMA library exactly once.

google-ima.js

/*global YUI*/
/**
 * Loads the google IMA library exactly once.
 *
 * https://developers.google.com/interactive-media-ads/docs/sdks/googlehtml5
 *
 * @module google-ima
 * @requires event-custom
 */
YUI.add("google-ima", function (Y) {
  var IMA_LOADED = "ima:loaded",
    win = Y.config.win,
    yLangIsFunction = Y.Lang.isFunction,
    loadTO,
    onLibLoaded = function (ima) {
      Y.Global.fire(IMA_LOADED, ima);
    },
    onLibSuccess = function () {
      onLibLoaded(win.google.ima);
    },
    onIMALoaded = function () {
      clearTimeout(loadTO);
      onLibLoaded(win.google.ima);
    },
    onGoogleLoaded = function () {
      var google = win.google;
      if (google && google.ima) {
        onLibSuccess(google.ima);
      } else if (google && google.load) {
        // if it takes longer than 10 seconds to load
        // cancel and call it an error
        loadTO = setTimeout(onLibLoaded, 10 * 1000);
        google.load("ima", "1", { callback: onIMALoaded });
      } else {
        onLibLoaded();
      }
    };

  if (!Y.Global.getEvent(IMA_LOADED, true)) {
    Y.Global.publish(IMA_LOADED, { fireOnce: true });
    if (win.google) {
      onGoogleLoaded();
    } else {
      Y.Get.script("http://www.google.com/jsapi", {
        onSuccess: onGoogleLoaded,
        onFailure: onLibLoaded
      });
    }
  }

  /**
   * loads the IMA library as quickly as possible, while only loading the
   * library exactly once.
   * @method loadGoogleIMA
   * @static
   * @for YUI
   * @param {Function} cb Called when the library is loaded. Passed the google.ima object as an argument.
   * @return {CustomEvent} An event handler for when the library is loaded.
   **/
  Y.loadGoogleIMA = function (cb) {
    return Y.Global.once(IMA_LOADED, function (g) {
      if (yLangIsFunction(cb)) {
        cb(g);
      }
    });
  };

}, "3.5.0", { requires: ["event-custom"] });