goog.Dependency.prototype.load = function()

in asdoc/library/closure/goog/base.js [3283:3387]
83 lines of code
18 McCabe index (conditional complexity)

  goog.Dependency.prototype.load = function(controller) {
    if (goog.global.CLOSURE_IMPORT_SCRIPT) {
      if (goog.global.CLOSURE_IMPORT_SCRIPT(this.path)) {
        controller.loaded();
      } else {
        controller.pause();
      }
      return;
    }

    if (!goog.inHtmlDocument_()) {
      goog.logToConsole_(
          'Cannot use default debug loader outside of HTML documents.');
      if (this.relativePath == 'deps.js') {
        // Some old code is relying on base.js auto loading deps.js failing with
        // no error before later setting CLOSURE_IMPORT_SCRIPT.
        // CLOSURE_IMPORT_SCRIPT should be set *before* base.js is loaded, or
        // CLOSURE_NO_DEPS set to true.
        goog.logToConsole_(
            'Consider setting CLOSURE_IMPORT_SCRIPT before loading base.js, ' +
            'or setting CLOSURE_NO_DEPS to true.');
        controller.loaded();
      } else {
        controller.pause();
      }
      return;
    }

    /** @type {!HTMLDocument} */
    var doc = goog.global.document;

    // If the user tries to require a new symbol after document load,
    // something has gone terribly wrong. Doing a document.write would
    // wipe out the page. This does not apply to the CSP-compliant method
    // of writing script tags.
    if (doc.readyState == 'complete' &&
        !goog.ENABLE_CHROME_APP_SAFE_SCRIPT_LOADING) {
      // Certain test frameworks load base.js multiple times, which tries
      // to write deps.js each time. If that happens, just fail silently.
      // These frameworks wipe the page between each load of base.js, so this
      // is OK.
      var isDeps = /\bdeps.js$/.test(this.path);
      if (isDeps) {
        controller.loaded();
        return;
      } else {
        throw Error('Cannot write "' + this.path + '" after document load');
      }
    }

    if (!goog.ENABLE_CHROME_APP_SAFE_SCRIPT_LOADING &&
        goog.isDocumentLoading_()) {
      var key = goog.Dependency.registerCallback_(function(script) {
        if (!goog.DebugLoader_.IS_OLD_IE_ || script.readyState == 'complete') {
          goog.Dependency.unregisterCallback_(key);
          controller.loaded();
        }
      });
      var nonceAttr = !goog.DebugLoader_.IS_OLD_IE_ && goog.getScriptNonce() ?
          ' nonce="' + goog.getScriptNonce() + '"' :
          '';
      var event =
          goog.DebugLoader_.IS_OLD_IE_ ? 'onreadystatechange' : 'onload';
      var defer = goog.Dependency.defer_ ? 'defer' : '';
      doc.write(
          '<script src="' + this.path + '" ' + event +
          '="goog.Dependency.callback_(\'' + key +
          '\', this)" type="text/javascript" ' + defer + nonceAttr + '><' +
          '/script>');
    } else {
      var scriptEl =
          /** @type {!HTMLScriptElement} */ (doc.createElement('script'));
      scriptEl.defer = goog.Dependency.defer_;
      scriptEl.async = false;
      scriptEl.type = 'text/javascript';

      // If CSP nonces are used, propagate them to dynamically created scripts.
      // This is necessary to allow nonce-based CSPs without 'strict-dynamic'.
      var nonce = goog.getScriptNonce();
      if (nonce) {
        scriptEl.setAttribute('nonce', nonce);
      }

      if (goog.DebugLoader_.IS_OLD_IE_) {
        // Execution order is not guaranteed on old IE, halt loading and write
        // these scripts one at a time, after each loads.
        controller.pause();
        scriptEl.onreadystatechange = function() {
          if (scriptEl.readyState == 'loaded' ||
              scriptEl.readyState == 'complete') {
            controller.loaded();
            controller.resume();
          }
        };
      } else {
        scriptEl.onload = function() {
          scriptEl.onload = null;
          controller.loaded();
        };
      }

      scriptEl.src = this.path;
      doc.head.appendChild(scriptEl);
    }
  };