• Overview
@angular/core

ApplicationRef

Class

A reference to an Angular application running on a page.

  
    class ApplicationRef {
}

destroyed

boolean

Indicates whether this instance was destroyed.

componentTypes

Type<any>[]

Get a list of component types registered to this application. This list is populated even before the component is created.

components

Get a list of components registered to this application.

isStable

Observable<boolean>

Returns an Observable that indicates when the application is stable or unstable.

whenStable

Promise<void>
@returnsPromise<void>

injector

The EnvironmentInjector used to create this application.

bootstrap

2 overloads

Bootstrap a component onto the element identified by its selector or, optionally, to a specified element.

@paramcomponentType<C>
@paramrootSelectorOrNodeany
@returnsComponentRef<C>
Usage notes

Bootstrap process

When bootstrapping a component, Angular mounts it onto a target DOM element and kicks off automatic change detection. The target DOM element can be provided using the rootSelectorOrNode argument.

If the target DOM element is not provided, Angular tries to find one on a page using the selector of the component that is being bootstrapped (first matched element is used).

Example

Generally, we define the component to bootstrap in the bootstrap array of NgModule, but it requires us to know the component while writing the application code.

Imagine a situation where we have to wait for an API call to decide about the component to bootstrap. We can use the ngDoBootstrap hook of the NgModule and call this method to dynamically bootstrap a component.

{@example core/ts/platform/platform.ts region='componentSelector'}

Optionally, a component can be mounted onto a DOM element that does not match the selector of the bootstrapped component.

In the following example, we are providing a CSS selector to match the target element.

{@example core/ts/platform/platform.ts region='cssSelector'}

While in this example, we are providing reference to a DOM node.

{@example core/ts/platform/platform.ts region='domNode'}

Bootstrap a component onto the element identified by its selector or, optionally, to a specified element.

@deprecated

Passing Component factories as the Application.bootstrap function argument is deprecated. Pass Component Types instead.

@paramcomponentFactoryComponentFactory<C>
@paramrootSelectorOrNodeany
@returnsComponentRef<C>
Usage notes

Bootstrap process

When bootstrapping a component, Angular mounts it onto a target DOM element and kicks off automatic change detection. The target DOM element can be provided using the rootSelectorOrNode argument.

If the target DOM element is not provided, Angular tries to find one on a page using the selector of the component that is being bootstrapped (first matched element is used).

Example

Generally, we define the component to bootstrap in the bootstrap array of NgModule, but it requires us to know the component while writing the application code.

Imagine a situation where we have to wait for an API call to decide about the component to bootstrap. We can use the ngDoBootstrap hook of the NgModule and call this method to dynamically bootstrap a component.

{@example core/ts/platform/platform.ts region='componentSelector'}

Optionally, a component can be mounted onto a DOM element that does not match the selector of the bootstrapped component.

In the following example, we are providing a CSS selector to match the target element.

{@example core/ts/platform/platform.ts region='cssSelector'}

While in this example, we are providing reference to a DOM node.

{@example core/ts/platform/platform.ts region='domNode'}

tick

void

Invoke this method to explicitly process change detection and its side-effects.

In development mode, tick() also performs a second change detection cycle to ensure that no further changes are detected. If additional changes are picked up during this second cycle, bindings in the app have side-effects that cannot be resolved in a single change detection pass. In this case, Angular throws an error, since an Angular application can only have one change detection pass during which all change detection must complete.

@returnsvoid

attachView

void

Attaches a view so that it will be dirty checked. The view will be automatically detached when it is destroyed. This will throw if the view is already attached to a ViewContainer.

@paramviewRefViewRef
@returnsvoid

detachView

void

Detaches a view from dirty checking again.

@paramviewRefViewRef
@returnsvoid

onDestroy

VoidFunction

Registers a listener to be called when an instance is destroyed.

@paramcallback() => void

A callback function to add as a listener.

@returnsVoidFunction

destroy

void

Destroys an Angular application represented by this ApplicationRef. Calling this function will destroy the associated environment injectors as well as all the bootstrapped components with their views.

@returnsvoid

viewCount

number

Returns the number of attached views.

Jump to details