text: /**
  @module @ember/application
  */
  
  import { dictionary } from 'ember-utils';
  import { ENV } from 'ember-environment';
  import { hasDOM } from 'ember-browser-environment';
  import { assert, isTesting } from '@ember/debug';
  import { DEBUG } from '@glimmer/env';
  import { bind, join, once, run, schedule } from '@ember/runloop';
  import { libraries, processAllNamespaces, setNamespaceSearchDisabled } from 'ember-metal';
  import { _loaded, runLoadHooks } from './lazy_load';
  import { RSVP } from 'ember-runtime';
  import { EventDispatcher, jQuery, jQueryDisabled } from 'ember-views';
  import {
    Route,
    Router,
    HashLocation,
    HistoryLocation,
    AutoLocation,
    NoneLocation,
    BucketCache,
  } from 'ember-routing';
  import ApplicationInstance from '../instance';
  import Engine from '@ember/engine';
  import { privatize as P } from 'container';
  import { setupApplicationRegistry } from 'ember-glimmer';
  import { RouterService } from 'ember-routing';
  import { EMBER_ROUTING_ROUTER_SERVICE } from '@ember/canary-features';
  
  let librariesRegistered = false;
  
  /**
    An instance of `Application` is the starting point for every Ember
    application. It helps to instantiate, initialize and coordinate the many
    objects that make up your app.
  
    Each Ember app has one and only one `Application` object. In fact, the
    very first thing you should do in your application is create the instance:
  
    ```javascript
    import Application from '@ember/application';
  
    window.App = Application.create();
    ```
  
    Typically, the application object is the only global variable. All other
    classes in your app should be properties on the `Application` instance,
    which highlights its first role: a global namespace.
  
    For example, if you define a view class, it might look like this:
  
    ```javascript
    import Application from '@ember/application';
  
    App.MyView = Ember.View.extend();
    ```
  
    By default, calling `Application.create()` will automatically initialize
    your application by calling the `Application.initialize()` method. If
    you need to delay initialization, you can call your app's `deferReadiness()`
    method. When you are ready for your app to be initialized, call its
    `advanceReadiness()` method.
  
    You can define a `ready` method on the `Application` instance, which
    will be run by Ember when the application is initialized.
  
    Because `Application` inherits from `Ember.Namespace`, any classes
    you create will have useful string representations when calling `toString()`.
    See the `Ember.Namespace` documentation for more information.
  
    While you can think of your `Application` as a container that holds the
    other classes in your application, there are several other responsibilities
    going on under-the-hood that you may want to understand.
  
    ### Event Delegation
  
    Ember uses a technique called _event delegation_. This allows the framework
    to set up a global, shared event listener instead of requiring each view to
    do it manually. For example, instead of each view registering its own
    `mousedown` listener on its associated element, Ember sets up a `mousedown`
    listener on the `body`.
  
    If a `mousedown` event occurs, Ember will look at the target of the event and
    start walking up the DOM node tree, finding corresponding views and invoking
    their `mouseDown` method as it goes.
  
    `Application` has a number of default events that it listens for, as
    well as a mapping from lowercase events to camel-cased view method names. For
    example, the `keypress` event causes the `keyPress` method on the view to be
    called, the `dblclick` event causes `doubleClick` to be called, and so on.
  
    If there is a bubbling browser event that Ember does not listen for by
    default, you can specify custom events and their corresponding view method
    names by setting the application's `customEvents` property:
  
    ```javascript
    import Application from '@ember/application';
  
    let App = Application.create({
      customEvents: {
        // add support for the paste event
        paste: 'paste'
      }
    });
    ```
  
    To prevent Ember from setting up a listener for a default event,
    specify the event name with a `null` value in the `customEvents`
    property:
  
    ```javascript
    import Application from '@ember/application';
  
    let App = Application.create({
      customEvents: {
        // prevent listeners for mouseenter/mouseleave events
        mouseenter: null,
        mouseleave: null
      }
    });
    ```
  
    By default, the application sets up these event listeners on the document
    body. However, in cases where you are embedding an Ember application inside
    an existing page, you may want it to set up the listeners on an element
    inside the body.
  
    For example, if only events inside a DOM element with the ID of `ember-app`
    should be delegated, set your application's `rootElement` property:
  
    ```javascript
    import Application from '@ember/application';
  
    let App = Application.create({
      rootElement: '#ember-app'
    });
    ```
  
    The `rootElement` can be either a DOM element or a jQuery-compatible selector
    string. Note that *views appended to the DOM outside the root element will
    not receive events.* If you specify a custom root element, make sure you only
    append views inside it!
  
    To learn more about the events Ember components use, see
  
    [components/handling-events](https://guides.emberjs.com/release/components/handling-events/#toc_event-names).
  
    ### Initializers
  
    Libraries on top of Ember can add initializers, like so:
  
    ```javascript
    import Application from '@ember/application';
  
    Application.initializer({
      name: 'api-adapter',
  
      initialize: function(application) {
        application.register('api-adapter:main', ApiAdapter);
      }
    });
    ```
  
    Initializers provide an opportunity to access the internal registry, which
    organizes the different components of an Ember application. Additionally
    they provide a chance to access the instantiated application. Beyond
    being used for libraries, initializers are also a great way to organize
    dependency injection or setup in your own application.
  
    ### Routing
  
    In addition to creating your application's router, `Application` is
    also responsible for telling the router when to start routing. Transitions
    between routes can be logged with the `LOG_TRANSITIONS` flag, and more
    detailed intra-transition logging can be logged with
    the `LOG_TRANSITIONS_INTERNAL` flag:
  
    ```javascript
    import Application from '@ember/application';
  
    let App = Application.create({
      LOG_TRANSITIONS: true, // basic logging of successful transitions
      LOG_TRANSITIONS_INTERNAL: true // detailed logging of all routing steps
    });
    ```
  
    By default, the router will begin trying to translate the current URL into
    application state once the browser emits the `DOMContentReady` event. If you
    need to defer routing, you can call the application's `deferReadiness()`
    method. Once routing can begin, call the `advanceReadiness()` method.
  
    If there is any setup required before routing begins, you can implement a
    `ready()` method on your app that will be invoked immediately before routing
    begins.
  
    @class Application
    @extends Engine
    @uses RegistryProxyMixin
    @public
  */
  
  const Application = Engine.extend({
    /**
      The root DOM element of the Application. This can be specified as an
      element or a
      [jQuery-compatible selector string](http://api.jquery.com/category/selectors/).
  
      This is the element that will be passed to the Application's,
      `eventDispatcher`, which sets up the listeners for event delegation. Every
      view in your application should be a child of the element you specify here.
  
      @property rootElement
      @type DOMElement
      @default 'body'
      @public
    */
    rootElement: 'body',
  
    /**
      The `Ember.EventDispatcher` responsible for delegating events to this
      application's views.
  
      The event dispatcher is created by the application at initialization time
      and sets up event listeners on the DOM element described by the
      application's `rootElement` property.
  
      See the documentation for `Ember.EventDispatcher` for more information.
  
      @property eventDispatcher
      @type Ember.EventDispatcher
      @default null
      @public
    */
    eventDispatcher: null,
  
    /**
      The DOM events for which the event dispatcher should listen.
  
      By default, the application's `Ember.EventDispatcher` listens
      for a set of standard DOM events, such as `mousedown` and
      `keyup`, and delegates them to your application's `Ember.View`
      instances.
  
      If you would like additional bubbling events to be delegated to your
      views, set your `Application`'s `customEvents` property
      to a hash containing the DOM event name as the key and the
      corresponding view method name as the value. Setting an event to
      a value of `null` will prevent a default event listener from being
      added for that event.
  
      To add new events to be listened to:
  
      ```javascript
      import Application from '@ember/application';
  
      let App = Application.create({
        customEvents: {
          // add support for the paste event
          paste: 'paste'
        }
      });
      ```
  
      To prevent default events from being listened to:
  
      ```javascript
      import Application from '@ember/application';
  
      let App = Application.create({
        customEvents: {
          // remove support for mouseenter / mouseleave events
          mouseenter: null,
          mouseleave: null
        }
      });
      ```
      @property customEvents
      @type Object
      @default null
      @public
    */
    customEvents: null,
  
    /**
      Whether the application should automatically start routing and render
      templates to the `rootElement` on DOM ready. While default by true,
      other environments such as FastBoot or a testing harness can set this
      property to `false` and control the precise timing and behavior of the boot
      process.
  
      @property autoboot
      @type Boolean
      @default true
      @private
    */
    autoboot: true,
  
    /**
      Whether the application should be configured for the legacy "globals mode".
      Under this mode, the Application object serves as a global namespace for all
      classes.
  
      ```javascript
      import Application from '@ember/application';
      import Component from '@ember/component';
  
      let App = Application.create({
        ...
      });
  
      App.Router.reopen({
        location: 'none'
      });
  
      App.Router.map({
        ...
      });
  
      App.MyComponent = Component.extend({
        ...
      });
      ```
  
      This flag also exposes other internal APIs that assumes the existence of
      a special "default instance", like `App.__container__.lookup(...)`.
  
      This option is currently not configurable, its value is derived from
      the `autoboot` flag – disabling `autoboot` also implies opting-out of
      globals mode support, although they are ultimately orthogonal concerns.
  
      Some of the global modes features are already deprecated in 1.x. The
      existence of this flag is to untangle the globals mode code paths from
      the autoboot code paths, so that these legacy features can be reviewed
      for deprecation/removal separately.
  
      Forcing the (autoboot=true, _globalsMode=false) here and running the tests
      would reveal all the places where we are still relying on these legacy
      behavior internally (mostly just tests).
  
      @property _globalsMode
      @type Boolean
      @default true
      @private
    */
    _globalsMode: true,
  
    /**
      An array of application instances created by `buildInstance()`. Used
      internally to ensure that all instances get destroyed.
  
      @property _applicationInstances
      @type Array
      @default null
      @private
    */
    _applicationInstances: null,
  
    init() {
      // eslint-disable-line no-unused-vars
      this._super(...arguments);
  
      if (!this.$) {
        this.$ = jQuery;
      }
  
      registerLibraries();
  
      if (DEBUG) {
        if (ENV.LOG_VERSION) {
          // we only need to see this once per Application#init
          ENV.LOG_VERSION = false;
          libraries.logVersions();
        }
      }
  
      // Start off the number of deferrals at 1. This will be decremented by
      // the Application's own `boot` method.
      this._readinessDeferrals = 1;
      this._booted = false;
      this._applicationInstances = new Set();
  
      this.autoboot = this._globalsMode = !!this.autoboot;
  
      if (this._globalsMode) {
        this._prepareForGlobalsMode();
      }
  
      if (this.autoboot) {
        this.waitForDOMReady();
      }
    },
  
    /**
      Create an ApplicationInstance for this application.
  
      @private
      @method buildInstance
      @return {ApplicationInstance} the application instance
    */
    buildInstance(options = {}) {
      options.base = this;
      options.application = this;
      return ApplicationInstance.create(options);
    },
  
    /**
      Start tracking an ApplicationInstance for this application.
      Used when the ApplicationInstance is created.
  
      @private
      @method _watchInstance
    */
    _watchInstance(instance) {
      this._applicationInstances.add(instance);
    },
  
    /**
      Stop tracking an ApplicationInstance for this application.
      Used when the ApplicationInstance is about to be destroyed.
  
      @private
      @method _unwatchInstance
    */
    _unwatchInstance(instance) {
      return this._applicationInstances.delete(instance);
    },
  
    /**
      Enable the legacy globals mode by allowing this application to act
      as a global namespace. See the docs on the `_globalsMode` property
      for details.
  
      Most of these features are already deprecated in 1.x, so we can
      stop using them internally and try to remove them.
  
      @private
      @method _prepareForGlobalsMode
    */
    _prepareForGlobalsMode() {
      // Create subclass of Router for this Application instance.
      // This is to ensure that someone reopening `App.Router` does not
      // tamper with the default `Router`.
      this.Router = (this.Router || Router).extend();
  
      this._buildDeprecatedInstance();
    },
  
    /*
      Build the deprecated instance for legacy globals mode support.
      Called when creating and resetting the application.
  
      This is orthogonal to autoboot: the deprecated instance needs to
      be created at Application construction (not boot) time to expose
      App.__container__. If autoboot sees that this instance exists,
      it will continue booting it to avoid doing unncessary work (as
      opposed to building a new instance at boot time), but they are
      otherwise unrelated.
  
      @private
      @method _buildDeprecatedInstance
    */
    _buildDeprecatedInstance() {
      // Build a default instance
      let instance = this.buildInstance();
  
      // Legacy support for App.__container__ and other global methods
      // on App that rely on a single, default instance.
      this.__deprecatedInstance__ = instance;
      this.__container__ = instance.__container__;
    },
  
    /**
      Automatically kick-off the boot process for the application once the
      DOM has become ready.
  
      The initialization itself is scheduled on the actions queue which
      ensures that code-loading finishes before booting.
  
      If you are asynchronously loading code, you should call `deferReadiness()`
      to defer booting, and then call `advanceReadiness()` once all of your code
      has finished loading.
  
      @private
      @method waitForDOMReady
    */
    waitForDOMReady() {
      if (!this.$ || this.$.isReady) {
        schedule('actions', this, 'domReady');
      } else {
        this.$().ready(bind(this, 'domReady'));
      }
    },
  
    /**
      This is the autoboot flow:
  
      1. Boot the app by calling `this.boot()`
      2. Create an instance (or use the `__deprecatedInstance__` in globals mode)
      3. Boot the instance by calling `instance.boot()`
      4. Invoke the `App.ready()` callback
      5. Kick-off routing on the instance
  
      Ideally, this is all we would need to do:
  
      ```javascript
      _autoBoot() {
        this.boot().then(() => {
          let instance = (this._globalsMode) ? this.__deprecatedInstance__ : this.buildInstance();
          return instance.boot();
        }).then((instance) => {
          App.ready();
          instance.startRouting();
        });
      }
      ```
  
      Unfortunately, we cannot actually write this because we need to participate
      in the "synchronous" boot process. While the code above would work fine on
      the initial boot (i.e. DOM ready), when `App.reset()` is called, we need to
      boot a new instance synchronously (see the documentation on `_bootSync()`
      for details).
  
      Because of this restriction, the actual logic of this method is located
      inside `didBecomeReady()`.
  
      @private
      @method domReady
    */
    domReady() {
      if (this.isDestroyed) {
        return;
      }
  
      this._bootSync();
  
      // Continues to `didBecomeReady`
    },
  
    /**
      Use this to defer readiness until some condition is true.
  
      Example:
  
      ```javascript
      import Application from '@ember/application';
  
      let App = Application.create();
  
      App.deferReadiness();
  
      // $ is a reference to the jQuery object/function
      import $ from 'jquery;
  
      $.getJSON('/auth-token', function(token) {
        App.token = token;
        App.advanceReadiness();
      });
      ```
  
      This allows you to perform asynchronous setup logic and defer
      booting your application until the setup has finished.
  
      However, if the setup requires a loading UI, it might be better
      to use the router for this purpose.
  
      @method deferReadiness
      @public
    */
    deferReadiness() {
      assert(
        'You must call deferReadiness on an instance of Application',
        this instanceof Application
      );
      assert(
        'You cannot defer readiness since the `ready()` hook has already been called.',
        this._readinessDeferrals > 0
      );
      this._readinessDeferrals++;
    },
  
    /**
      Call `advanceReadiness` after any asynchronous setup logic has completed.
      Each call to `deferReadiness` must be matched by a call to `advanceReadiness`
      or the application will never become ready and routing will not begin.
  
      @method advanceReadiness
      @see {Application#deferReadiness}
      @public
    */
    advanceReadiness() {
      assert(
        'You must call advanceReadiness on an instance of Application',
        this instanceof Application
      );
      this._readinessDeferrals--;
  
      if (this._readinessDeferrals === 0) {
        once(this, this.didBecomeReady);
      }
    },
  
    /**
      Initialize the application and return a promise that resolves with the `Application`
      object when the boot process is complete.
  
      Run any application initializers and run the application load hook. These hooks may
      choose to defer readiness. For example, an authentication hook might want to defer
      readiness until the auth token has been retrieved.
  
      By default, this method is called automatically on "DOM ready"; however, if autoboot
      is disabled, this is automatically called when the first application instance is
      created via `visit`.
  
      @public
      @method boot
      @return {Promise<Application,Error>}
    */
    boot() {
      if (this._bootPromise) {
        return this._bootPromise;
      }
  
      try {
        this._bootSync();
      } catch (_) {
        // Ignore the error: in the asynchronous boot path, the error is already reflected
        // in the promise rejection
      }
  
      return this._bootPromise;
    },
  
    /**
      Unfortunately, a lot of existing code assumes the booting process is
      "synchronous". Specifically, a lot of tests assumes the last call to
      `app.advanceReadiness()` or `app.reset()` will result in the app being
      fully-booted when the current runloop completes.
  
      We would like new code (like the `visit` API) to stop making this assumption,
      so we created the asynchronous version above that returns a promise. But until
      we have migrated all the code, we would have to expose this method for use
      *internally* in places where we need to boot an app "synchronously".
  
      @private
    */
    _bootSync() {
      if (this._booted) {
        return;
      }
  
      // Even though this returns synchronously, we still need to make sure the
      // boot promise exists for book-keeping purposes: if anything went wrong in
      // the boot process, we need to store the error as a rejection on the boot
      // promise so that a future caller of `boot()` can tell what failed.
      let defer = (this._bootResolver = RSVP.defer());
      this._bootPromise = defer.promise;
  
      try {
        this.runInitializers();
        runLoadHooks('application', this);
        this.advanceReadiness();
        // Continues to `didBecomeReady`
      } catch (error) {
        // For the asynchronous boot path
        defer.reject(error);
  
        // For the synchronous boot path
        throw error;
      }
    },
  
    /**
      Reset the application. This is typically used only in tests. It cleans up
      the application in the following order:
  
      1. Deactivate existing routes
      2. Destroy all objects in the container
      3. Create a new application container
      4. Re-route to the existing url
  
      Typical Example:
  
      ```javascript
      import Application from '@ember/application';
      let App;
  
      run(function() {
        App = Application.create();
      });
  
      module('acceptance test', {
        setup: function() {
          App.reset();
        }
      });
  
      test('first test', function() {
        // App is freshly reset
      });
  
      test('second test', function() {
        // App is again freshly reset
      });
      ```
  
      Advanced Example:
  
      Occasionally you may want to prevent the app from initializing during
      setup. This could enable extra configuration, or enable asserting prior
      to the app becoming ready.
  
      ```javascript
      import Application from '@ember/application';
      let App;
  
      run(function() {
        App = Application.create();
      });
  
      module('acceptance test', {
        setup: function() {
          run(function() {
            App.reset();
            App.deferReadiness();
          });
        }
      });
  
      test('first test', function() {
        ok(true, 'something before app is initialized');
  
        run(function() {
          App.advanceReadiness();
        });
  
        ok(true, 'something after app is initialized');
      });
      ```
  
      @method reset
      @public
    */
    reset() {
      assert(
        `Calling reset() on instances of \`Application\` is not
              supported when globals mode is disabled; call \`visit()\` to
              create new \`ApplicationInstance\`s and dispose them
              via their \`destroy()\` method instead.`,
        this._globalsMode && this.autoboot
      );
  
      let instance = this.__deprecatedInstance__;
  
      this._readinessDeferrals = 1;
      this._bootPromise = null;
      this._bootResolver = null;
      this._booted = false;
  
      function handleReset() {
        run(instance, 'destroy');
        this._buildDeprecatedInstance();
        schedule('actions', this, '_bootSync');
      }
  
      join(this, handleReset);
    },
  
    /**
      @private
      @method didBecomeReady
    */
    didBecomeReady() {
      try {
        // TODO: Is this still needed for _globalsMode = false?
        if (!isTesting()) {
          // Eagerly name all classes that are already loaded
          processAllNamespaces();
          setNamespaceSearchDisabled(true);
        }
  
        // See documentation on `_autoboot()` for details
        if (this.autoboot) {
          let instance;
  
          if (this._globalsMode) {
            // If we already have the __deprecatedInstance__ lying around, boot it to
            // avoid unnecessary work
            instance = this.__deprecatedInstance__;
          } else {
            // Otherwise, build an instance and boot it. This is currently unreachable,
            // because we forced _globalsMode to === autoboot; but having this branch
            // allows us to locally toggle that flag for weeding out legacy globals mode
            // dependencies independently
            instance = this.buildInstance();
          }
  
          instance._bootSync();
  
          // TODO: App.ready() is not called when autoboot is disabled, is this correct?
          this.ready();
  
          instance.startRouting();
        }
  
        // For the asynchronous boot path
        this._bootResolver.resolve(this);
  
        // For the synchronous boot path
        this._booted = true;
      } catch (error) {
        // For the asynchronous boot path
        this._bootResolver.reject(error);
  
        // For the synchronous boot path
        throw error;
      }
    },
  
    /**
      Called when the Application has become ready, immediately before routing
      begins. The call will be delayed until the DOM has become ready.
  
      @event ready
      @public
    */
    ready() {
      return this;
    },
  
    // This method must be moved to the application instance object
    willDestroy() {
      this._super(...arguments);
      setNamespaceSearchDisabled(false);
      this._booted = false;
      this._bootPromise = null;
      this._bootResolver = null;
  
      if (_loaded.application === this) {
        _loaded.application = undefined;
      }
  
      if (this._applicationInstances.size) {
        this._applicationInstances.forEach(i => i.destroy());
        this._applicationInstances.clear();
      }
    },
  
    /**
      Boot a new instance of `ApplicationInstance` for the current
      application and navigate it to the given `url`. Returns a `Promise` that
      resolves with the instance when the initial routing and rendering is
      complete, or rejects with any error that occurred during the boot process.
  
      When `autoboot` is disabled, calling `visit` would first cause the
      application to boot, which runs the application initializers.
  
      This method also takes a hash of boot-time configuration options for
      customizing the instance's behavior. See the documentation on
      `ApplicationInstance.BootOptions` for details.
  
      `ApplicationInstance.BootOptions` is an interface class that exists
      purely to document the available options; you do not need to construct it
      manually. Simply pass a regular JavaScript object containing of the
      desired options:
  
      ```javascript
      MyApp.visit("/", { location: "none", rootElement: "#container" });
      ```
  
      ### Supported Scenarios
  
      While the `BootOptions` class exposes a large number of knobs, not all
      combinations of them are valid; certain incompatible combinations might
      result in unexpected behavior.
  
      For example, booting the instance in the full browser environment
      while specifying a foreign `document` object (e.g. `{ isBrowser: true,
      document: iframe.contentDocument }`) does not work correctly today,
      largely due to Ember's jQuery dependency.
  
      Currently, there are three officially supported scenarios/configurations.
      Usages outside of these scenarios are not guaranteed to work, but please
      feel free to file bug reports documenting your experience and any issues
      you encountered to help expand support.
  
      #### Browser Applications (Manual Boot)
  
      The setup is largely similar to how Ember works out-of-the-box. Normally,
      Ember will boot a default instance for your Application on "DOM ready".
      However, you can customize this behavior by disabling `autoboot`.
  
      For example, this allows you to render a miniture demo of your application
      into a specific area on your marketing website:
  
      ```javascript
      import MyApp from 'my-app';
  
      $(function() {
        let App = MyApp.create({ autoboot: false });
  
        let options = {
          // Override the router's location adapter to prevent it from updating
          // the URL in the address bar
          location: 'none',
  
          // Override the default `rootElement` on the app to render into a
          // specific `div` on the page
          rootElement: '#demo'
        };
  
        // Start the app at the special demo URL
        App.visit('/demo', options);
      });
      ```
  
      Or perhaps you might want to boot two instances of your app on the same
      page for a split-screen multiplayer experience:
  
      ```javascript
      import MyApp from 'my-app';
  
      $(function() {
        let App = MyApp.create({ autoboot: false });
  
        let sessionId = MyApp.generateSessionID();
  
        let player1 = App.visit(`/matches/join?name=Player+1&session=${sessionId}`, { rootElement: '#left', location: 'none' });
        let player2 = App.visit(`/matches/join?name=Player+2&session=${sessionId}`, { rootElement: '#right', location: 'none' });
  
        Promise.all([player1, player2]).then(() => {
          // Both apps have completed the initial render
          $('#loading').fadeOut();
        });
      });
      ```
  
      Do note that each app instance maintains their own registry/container, so
      they will run in complete isolation by default.
  
      #### Server-Side Rendering (also known as FastBoot)
  
      This setup allows you to run your Ember app in a server environment using
      Node.js and render its content into static HTML for SEO purposes.
  
      ```javascript
      const HTMLSerializer = new SimpleDOM.HTMLSerializer(SimpleDOM.voidMap);
  
      function renderURL(url) {
        let dom = new SimpleDOM.Document();
        let rootElement = dom.body;
        let options = { isBrowser: false, document: dom, rootElement: rootElement };
  
        return MyApp.visit(options).then(instance => {
          try {
            return HTMLSerializer.serialize(rootElement.firstChild);
          } finally {
            instance.destroy();
          }
        });
      }
      ```
  
      In this scenario, because Ember does not have access to a global `document`
      object in the Node.js environment, you must provide one explicitly. In practice,
      in the non-browser environment, the stand-in `document` object only needs to
      implement a limited subset of the full DOM API. The `SimpleDOM` library is known
      to work.
  
      Since there is no access to jQuery in the non-browser environment, you must also
      specify a DOM `Element` object in the same `document` for the `rootElement` option
      (as opposed to a selector string like `"body"`).
  
      See the documentation on the `isBrowser`, `document` and `rootElement` properties
      on `ApplicationInstance.BootOptions` for details.
  
      #### Server-Side Resource Discovery
  
      This setup allows you to run the routing layer of your Ember app in a server
      environment using Node.js and completely disable rendering. This allows you
      to simulate and discover the resources (i.e. AJAX requests) needed to fulfill
      a given request and eagerly "push" these resources to the client.
  
      ```app/initializers/network-service.js
      import BrowserNetworkService from 'app/services/network/browser';
      import NodeNetworkService from 'app/services/network/node';
  
      // Inject a (hypothetical) service for abstracting all AJAX calls and use
      // the appropriate implementation on the client/server. This also allows the
      // server to log all the AJAX calls made during a particular request and use
      // that for resource-discovery purpose.
  
      export function initialize(application) {
        if (window) { // browser
          application.register('service:network', BrowserNetworkService);
        } else { // node
          application.register('service:network', NodeNetworkService);
        }
  
        application.inject('route', 'network', 'service:network');
      };
  
      export default {
        name: 'network-service',
        initialize: initialize
      };
      ```
  
      ```app/routes/post.js
      import Route from '@ember/routing/route';
  
      // An example of how the (hypothetical) service is used in routes.
  
      export default Route.extend({
        model(params) {
          return this.network.fetch(`/api/posts/${params.post_id}.json`);
        },
  
        afterModel(post) {
          if (post.isExternalContent) {
            return this.network.fetch(`/api/external/?url=${post.externalURL}`);
          } else {
            return post;
          }
        }
      });
      ```
  
      ```javascript
      // Finally, put all the pieces together
  
      function discoverResourcesFor(url) {
        return MyApp.visit(url, { isBrowser: false, shouldRender: false }).then(instance => {
          let networkService = instance.lookup('service:network');
          return networkService.requests; // => { "/api/posts/123.json": "..." }
        });
      }
      ```
  
      @public
      @method visit
      @param url {String} The initial URL to navigate to
      @param options {ApplicationInstance.BootOptions}
      @return {Promise<ApplicationInstance, Error>}
    */
    visit(url, options) {
      return this.boot().then(() => {
        let instance = this.buildInstance();
  
        return instance
          .boot(options)
          .then(() => instance.visit(url))
          .catch(error => {
            run(instance, 'destroy');
            throw error;
          });
      });
    },
  });
  
  Application.reopenClass({
    /**
      This creates a registry with the default Ember naming conventions.
  
      It also configures the registry:
  
      * registered views are created every time they are looked up (they are
        not singletons)
      * registered templates are not factories; the registered value is
        returned directly.
      * the router receives the application as its `namespace` property
      * all controllers receive the router as their `target` and `controllers`
        properties
      * all controllers receive the application as their `namespace` property
      * the application view receives the application controller as its
        `controller` property
      * the application view receives the application template as its
        `defaultTemplate` property
  
      @method buildRegistry
      @static
      @param {Application} namespace the application for which to
        build the registry
      @return {Ember.Registry} the built registry
      @private
    */
    buildRegistry() {
      // eslint-disable-line no-unused-vars
      let registry = this._super(...arguments);
  
      commonSetupRegistry(registry);
  
      setupApplicationRegistry(registry);
  
      return registry;
    },
  });
  
  function commonSetupRegistry(registry) {
    registry.register('router:main', Router.extend());
    registry.register('-view-registry:main', {
      create() {
        return dictionary(null);
      },
    });
  
    registry.register('route:basic', Route);
    registry.register('event_dispatcher:main', EventDispatcher);
  
    registry.injection('router:main', 'namespace', 'application:main');
  
    registry.register('location:auto', AutoLocation);
    registry.register('location:hash', HashLocation);
    registry.register('location:history', HistoryLocation);
    registry.register('location:none', NoneLocation);
  
    registry.register(P`-bucket-cache:main`, {
      create() {
        return new BucketCache();
      },
    });
  
    if (EMBER_ROUTING_ROUTER_SERVICE) {
      registry.register('service:router', RouterService);
      registry.injection('service:router', '_router', 'router:main');
    }
  }
  
  function registerLibraries() {
    if (!librariesRegistered) {
      librariesRegistered = true;
  
      if (hasDOM && !jQueryDisabled) {
        libraries.registerCoreLibrary('jQuery', jQuery().jquery);
      }
    }
  }
  
  export default Application;
  