@angular/core

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Angular/docs/9/api/core


@angular/core

package

Implements Angular's core functionality, low-level services, and utilities.

  • Defines the class infrastructure for components, view hierarchies, change detection, rendering, and event handling.
  • Defines the decorators that supply metadata and context for Angular constructs.
  • Defines infrastructure for dependency injection (DI), internationalization (i18n), and various testing and debugging facilities.

Entry points

Primary

@angular/core Implements Angular's core functionality, low-level services, and utilities.

Secondary

@angular/core/global Exposes a set of functions in the global namespace which are useful for debugging the current state of your application. These functions are exposed via the global ng "namespace" variable automatically when you import from @angular/core and run your application in development mode. These functions are not exposed when the application runs in a production mode.
@angular/core/testing Provides infrastructure for testing Angular core functionality.

Primary entry point exports

NgModules

ApplicationModule Configures the root injector for an app with providers of @angular/core dependencies that ApplicationRef needs to bootstrap components.

Classes

ApplicationInitStatus A class that reflects the state of running APP_INITIALIZERs.
ChangeDetectorRef Base class for Angular Views, provides change detection functionality. A change-detection tree collects all views that are to be checked for changes. Use the methods to add and remove views from the tree, initiate change-detection, and explicitly mark views as dirty, meaning that they have changed and need to be rerendered.
Compiler Low-level service for running the angular compiler during runtime to create ComponentFactorys, which can later be used to create and render a Component instance.
CompilerFactory A factory for creating a Compiler
ComponentFactory Base class for a factory that can create a component dynamically. Instantiate a factory for a given type of component with resolveComponentFactory(). Use the resulting ComponentFactory.create() method to create a component of that type.
ComponentFactoryResolver A simple registry that maps Components to generated ComponentFactory classes that can be used to create instances of components. Use to obtain the factory for a given component type, then use the factory's create() method to create a component of that type.
ComponentRef Represents a component created by a ComponentFactory. Provides access to the component instance and related objects, and provides the means of destroying the instance.
DebugEventListener
DefaultIterableDiffer Deprecated: v4.0.0 - Should not be part of public API.
ElementRef A wrapper around a native element inside of a View.
EmbeddedViewRef Represents an Angular view in a view container. An embedded view can be referenced from a component other than the hosting component whose template defines it, or it can be defined independently by a TemplateRef.
ErrorHandler Provides a hook for centralized exception handling.
EventEmitter Use in components with the @Output directive to emit custom events synchronously or asynchronously, and register handlers for those events by subscribing to an instance.
InjectionToken Creates a token that can be used in a DI Provider.
Injector Concrete injectors implement this interface. Injectors are configured with providers that associate dependencies of various types with injection tokens.
IterableDiffers A repository of different iterable diffing strategies used by NgFor, NgClass, and others.
KeyValueDiffers A repository of different Map diffing strategies used by NgClass, NgStyle, and others.
ModuleWithComponentFactories Combination of NgModuleFactory and ComponentFactorys.
NgModuleFactory
NgModuleFactoryLoader

Deprecated: the string form of loadChildren is deprecated, and NgModuleFactoryLoader is part of its implementation. See LoadChildren for more details.

Used to load ng module factories.

NgModuleRef Represents an instance of an NgModule created via a NgModuleFactory.
NgProbeToken A token for third-party components that can register themselves with NgProbe.
NgZone An injectable service for executing work inside or outside of the Angular zone.
Query Base class for query metadata.
QueryList An unmodifiable list of items that Angular keeps up to date when the state of the application changes.
ReflectiveInjector

Deprecated: from v5 - slow and brings in a lot of code, Use Injector.create instead.

A ReflectiveDependency injection container used for instantiating objects and resolving dependencies.

ReflectiveKey

Deprecated: No replacement

A unique object used for retrieving items from the ReflectiveInjector.

Renderer2 Extend this base class to implement custom rendering. By default, Angular renders a template into DOM. You can use custom rendering to intercept rendering calls, or to render to something other than DOM.
RendererFactory2 Creates and initializes a custom renderer that implements the Renderer2 base class.
ResolvedReflectiveFactory An internal resolved representation of a factory function created by resolving Provider.
Sanitizer Sanitizer is used by the views to sanitize potentially dangerous values.
SimpleChange Represents a basic change from a previous to a new value for a single property on a directive instance. Passed as a value in a SimpleChanges object to the ngOnChanges hook.
SystemJsNgModuleLoader

Deprecated: the string form of loadChildren is deprecated, and SystemJsNgModuleLoader is part of its implementation. See LoadChildren for more details.

NgModuleFactoryLoader that uses SystemJS to load NgModuleFactory

SystemJsNgModuleLoaderConfig

Deprecated: the string form of loadChildren is deprecated, and SystemJsNgModuleLoaderConfig is part of its implementation. See LoadChildren for more details.

Configuration for SystemJsNgModuleLoader. token.

TemplateRef Represents an embedded template that can be used to instantiate embedded views. To instantiate embedded views based on a template, use the ViewContainerRef method createEmbeddedView().
Testability The Testability service provides testing hooks that can be accessed from the browser and by services such as Protractor. Each bootstrapped Angular application on the page will have an instance of Testability.
TestabilityRegistry A global registry of Testability instances for specific elements.
Version Represents the version of Angular
ViewContainerRef Represents a container where one or more views can be attached to a component.
ViewRef Represents an Angular view, specifically the host view that is defined by a component. Also serves as the base class that adds destroy methods for embedded views.
WrappedValue Indicates that the result of a Pipe transformation has changed even though the reference has not changed.

Decorators

Attribute Parameter decorator for a directive constructor that designates a host-element attribute whose value is injected as a constant string literal.
Component Decorator that marks a class as an Angular component and provides configuration metadata that determines how the component should be processed, instantiated, and used at runtime.
ContentChild Parameter decorator that configures a content query.
ContentChildren Parameter decorator that configures a content query.
Directive Decorator that marks a class as an Angular directive. You can define your own directives to attach custom behavior to elements in the DOM.
Host Parameter decorator on a view-provider parameter of a class constructor that tells the DI framework to resolve the view by checking injectors of child elements, and stop when reaching the host element of the current component.
HostBinding Decorator that marks a DOM property as a host-binding property and supplies configuration metadata. Angular automatically checks host property bindings during change detection, and if a binding changes it updates the host element of the directive.
HostListener Decorator that declares a DOM event to listen for, and provides a handler method to run when that event occurs.
Inject Parameter decorator on a dependency parameter of a class constructor that specifies a custom provider of the dependency.
Injectable Decorator that marks a class as available to be provided and injected as a dependency.
Input Decorator that marks a class field as an input property and supplies configuration metadata. The input property is bound to a DOM property in the template. During change detection, Angular automatically updates the data property with the DOM property's value.
NgModule Decorator that marks a class as an NgModule and supplies configuration metadata.
Optional Parameter decorator to be used on constructor parameters, which marks the parameter as being an optional dependency. The DI framework provides null if the dependency is not found.
Output Decorator that marks a class field as an output property and supplies configuration metadata. The DOM property bound to the output property is automatically updated during change detection.
Pipe Decorator that marks a class as pipe and supplies configuration metadata.
Self Parameter decorator to be used on constructor parameters, which tells the DI framework to start dependency resolution from the local injector.
SkipSelf Parameter decorator to be used on constructor parameters, which tells the DI framework to start dependency resolution from the parent injector. Resolution works upward through the injector hierarchy, so the local injector is not checked for a provider.
ViewChild Property decorator that configures a view query. The change detector looks for the first element or the directive matching the selector in the view DOM. If the view DOM changes, and a new child matches the selector, the property is updated.
ViewChildren Parameter decorator that configures a view query.

Functions

asNativeElements
assertPlatform Checks that there currently is a platform which contains the given token as a provider.
createPlatform Creates a platform. Platforms have to be eagerly created via this function.
createPlatformFactory Creates a factory for a platform
destroyPlatform Destroy the existing platform.
enableProdMode Disable Angular's development mode, which turns off assertions and other checks within the framework.
forwardRef Allows to refer to references which are not yet defined.
getPlatform Returns the current platform.
isDevMode Returns whether Angular is in development mode. After called once, the value is locked and won't change any more.
resolveForwardRef Lazily retrieves the reference value from a forwardRef.
setTestabilityGetter Set the GetTestability implementation used by the Angular testing framework.

Structures

AbstractType Represents an abstract class T, if applied to a concrete class it would stop being instantiatable.
AfterContentChecked A lifecycle hook that is called after the default change detector has completed checking all content of a directive.
AfterContentInit A lifecycle hook that is called after Angular has fully initialized all content of a directive. Define an ngAfterContentInit() method to handle any additional initialization tasks.
AfterViewChecked A lifecycle hook that is called after the default change detector has completed checking a component's view for changes.
AfterViewInit A lifecycle hook that is called after Angular has fully initialized a component's view. Define an ngAfterViewInit() method to handle any additional initialization tasks.
ApplicationRef A reference to an Angular application running on a page.
ChangeDetectionStrategy The strategy that the default change detector uses to detect changes. When set, takes effect the next time change detection is triggered.
ClassProvider Configures the Injector to return an instance of useClass for a token.
ClassSansProvider Configures the Injector to return a value by invoking a useClass function. Base for ClassProvider decorator.
CollectionChangeRecord Deprecated: v4.0.0 - Use IterableChangeRecord instead.
ConstructorProvider Configures the Injector to return an instance of a token.
ConstructorSansProvider Configures the Injector to return an instance of a token.
DebugElement
DebugNode
DoBootstrap Hook for manual bootstrapping of the application instead of using bootstrap array in @NgModule annotation.
DoCheck A lifecycle hook that invokes a custom change-detection function for a directive, in addition to the check performed by the default change-detector.
ExistingProvider Configures the Injector to return a value of another useExisting token.
ExistingSansProvider Configures the Injector to return a value of another useExisting token.
FactoryProvider Configures the Injector to return a value by invoking a useFactory function.
FactorySansProvider Configures the Injector to return a value by invoking a useFactory function.
ForwardRefFn An interface that a function passed into forwardRef has to implement.
GetTestability Adapter interface for retrieving the Testability service associated for a particular context.
InjectFlags Injection flags for DI.
InjectableType A Type which has an InjectableDef static field.
InjectorType A type which has an InjectorDef static field.
IterableChangeRecord Record representing the item change information.
IterableChanges An object describing the changes in the Iterable collection since last time IterableDiffer#diff() was invoked.
IterableDiffer A strategy for tracking changes over time to an iterable. Used by NgForOf to respond to changes in an iterable by effecting equivalent changes in the DOM.
IterableDifferFactory Provides a factory for IterableDiffer.
KeyValueChangeRecord Record representing the item change information.
KeyValueChanges An object describing the changes in the Map or {[k:string]: string} since last time KeyValueDiffer#diff() was invoked.
KeyValueDiffer A differ that tracks changes made to an object over time.
KeyValueDifferFactory Provides a factory for KeyValueDiffer.
MissingTranslationStrategy

Use this enum at bootstrap as an option of bootstrapModule to define the strategy that the compiler should use in case of missing translations:

  • Error: throw if you have missing translations.
  • Warning (default): show a warning in the console and/or shell.
  • Ignore: do nothing.
ModuleWithProviders A wrapper around an NgModule that associates it with the providers.
OnChanges A lifecycle hook that is called when any data-bound property of a directive changes. Define an ngOnChanges() method to handle the changes.
OnDestroy A lifecycle hook that is called when a directive, pipe, or service is destroyed. Use for any custom cleanup that needs to occur when the instance is destroyed.
OnInit A lifecycle hook that is called after Angular has initialized all data-bound properties of a directive. Define an ngOnInit() method to handle any additional initialization tasks.
PipeTransform An interface that is implemented by pipes in order to perform a transformation. Angular invokes the transform method with the value of a binding as the first argument, and any parameters as the second argument in list form.
PlatformRef The Angular platform is the entry point for Angular on a web page. Each page has exactly one platform, and services (such as reflection) which are common to every Angular application running on the page are bound in its scope.
Predicate A boolean-valued function over a value, possibly including context information regarding that value's position in an array.
RendererStyleFlags2 Flags for renderer-specific style modifiers.
RendererType2 Used by RendererFactory2 to associate custom rendering data and styles with a rendering implementation.
ResolvedReflectiveProvider An internal resolved representation of a Provider used by the Injector.
SchemaMetadata A schema definition associated with an NgModule.
SecurityContext A SecurityContext marks a location that has dangerous security implications, e.g. a DOM property like innerHTML that could cause Cross Site Scripting (XSS) security bugs when improperly handled.
SimpleChanges A hashtable of changes represented by SimpleChange objects stored at the declared property name they belong to on a Directive or Component. This is the type passed to the ngOnChanges hook.
StaticClassProvider Configures the Injector to return an instance of useClass for a token.
StaticClassSansProvider Configures the Injector to return an instance of useClass for a token. Base for StaticClassProvider decorator.
TrackByFunction An optional function passed into the NgForOf directive that defines how to track changes for items in an iterable. The function takes the iteration index and item ID. When supplied, Angular tracks changes by the return value of the function.
Type Represents a type that a Component or other object is instances of.
TypeDecorator An interface implemented by all Angular type decorators, which allows them to be used as decorators as well as Angular syntax.
TypeProvider Configures the Injector to return an instance of Type when `Type' is used as the token.
ValueProvider Configures the Injector to return a value for a token.
ValueSansProvider Configures the Injector to return a value for a token. Base for ValueProvider decorator.
ViewEncapsulation Defines template and style encapsulation options available for Component's Component.

Types

ANALYZE_FOR_ENTRY_COMPONENTS

Deprecated: Since 9.0.0. With Ivy, this property is no longer necessary.

A DI token that you can use to create a virtual provider that will populate the entryComponents field of components and NgModules based on its useValue property value. All components that are referenced in the useValue value (either directly or in a nested array or map) are added to the entryComponents property.

APP_BOOTSTRAP_LISTENER All callbacks provided via this token will be called for every component that is bootstrapped. Signature of the callback:
APP_ID A DI Token representing a unique string id assigned to the application by Angular and used primarily for prefixing application attributes and CSS styles when ViewEncapsulation.Emulated is being used.
APP_INITIALIZER An injection token that allows you to provide one or more initialization functions. These function are injected at application startup and executed during app initialization. If any of these functions returns a Promise, initialization does not complete until the Promise is resolved.
COMPILER_OPTIONS Token to provide CompilerOptions in the platform injector.
CUSTOM_ELEMENTS_SCHEMA

Defines a schema that allows an NgModule to contain the following:

  • Non-Angular elements named with dash case (-).
  • Element properties named with dash case (-). Dash case is the naming convention for custom elements.
CompilerOptions Options for creating a compiler
DEFAULT_CURRENCY_CODE Provide this token to set the default currency code your application uses for CurrencyPipe when there is no currency code passed into it. This is only used by CurrencyPipe and has no relation to locale currency. Defaults to USD if not configured.
INJECTOR An InjectionToken that gets the current Injector for createInjector()-style injectors.
InjectableProvider Injectable providers used in @Injectable decorator.
LOCALE_ID Provide this token to set the locale of your application. It is used for i18n extraction, by i18n pipes (DatePipe, I18nPluralPipe, CurrencyPipe, DecimalPipe and PercentPipe) and by ICU expressions.
NO_ERRORS_SCHEMA Defines a schema that allows any property on any element.
NgIterable A type describing supported iterable types.
PACKAGE_ROOT_URL A token which indicates the root directory of the application
PLATFORM_ID A token that indicates an opaque platform id.
PLATFORM_INITIALIZER A function that will be executed when a platform is initialized.
Provider Describes how the Injector should be configured.
StaticProvider Describes how an Injector should be configured as static (that is, without reflection). A static provider provides tokens to an injector for various types of dependencies.
TRANSLATIONS Use this token at bootstrap to provide the content of your translation file (xtb, xlf or xlf2) when you want to translate your application in another language.
TRANSLATIONS_FORMAT Provide this token at bootstrap to set the format of your TRANSLATIONS: xtb, xlf or xlf2.
defineInjectable Deprecated: in v8, delete after v10. This API should be used only be generated code, and that code should now use ɵɵdefineInjectable instead.
getDebugNode
getModuleFactory Returns the NgModuleFactory with the given id, if it exists and has been loaded. Factories for modules that do not specify an id cannot be retrieved. Throws if the module cannot be found.
inject Injects a token from the currently active injector.
platformCore This platform has to be included in any other platform


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Licensed under the Creative Commons Attribution License 4.0.
https://v9.angular.io/api/core