add files properly
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parent
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p.location-badge.
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exported from <a href="/angular2/annotations.html">angular2/annotations</a>
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defined in <a href="https://github.com/angular/angular/tree/master/modules/angular2/src/core/annotations/annotations.js#L521">angular2/src/core/annotations/annotations.js (line 521)</a>
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:markdown
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Declare reusable UI building blocks for an application.
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Each Angular component requires a single `@Component` and at least one `@View` annotation. The `@Component`
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annotation specifies when a component is instantiated, and which properties and hostListeners it binds to.
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When a component is instantiated, Angular
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- creates a shadow DOM for the component.
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- loads the selected template into the shadow DOM.
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- creates a child <a href="../di/Injector-class.html"><code>Injector</code></a> which is configured with the `injectables` for the <a href="Component-class.html"><code>Component</code></a>.
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All template expressions and statements are then evaluated against the component instance.
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For details on the `@View` annotation, see <a href="View-class.html"><code>View</code></a>.
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## Example
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```
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@Component({
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selector: 'greet'
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})
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@View({
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template: 'Hello {{name}}!'
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})
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class Greet {
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name: string;
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constructor() {
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this.name = 'World';
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}
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}
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```
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.l-main-section
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h2 Members
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.l-sub-section
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h3 constructor
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pre.prettyprint
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code.
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constructor({
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selector,
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properties,
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events,
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hostListeners,
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injectables,
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lifecycle,
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changeDetection = DEFAULT
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}:{
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selector:string,
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properties:Object,
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events:List,
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hostListeners:Object,
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injectables:List,
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lifecycle:List,
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changeDetection:string
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}={})
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:markdown
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.l-sub-section
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h3 changeDetection
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:markdown
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Defines the used change detection strategy.
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When a component is instantiated, Angular creates a change detector, which is responsible for propagating
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the component's bindings.
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The `changeDetection` property defines, whether the change detection will be checked every time or only when the component
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tells it to do so.
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.l-sub-section
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h3 injectables
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:markdown
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Defines the set of injectable objects that are visible to a Component and its children.
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The `injectables` defined in the Component annotation allow you to configure a set of bindings for the component's
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injector.
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When a component is instantiated, Angular creates a new child Injector, which is configured with the bindings in
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the Component `injectables` annotation. The injectable objects then become available for injection to the component
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itself and any of the directives in the component's template, i.e. they are not available to the directives which
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are children in the component's light DOM.
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The syntax for configuring the `injectables` injectable is identical to <a href="../di/Injector-class.html"><code>Injector</code></a> injectable configuration.
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See <a href="../di/Injector-class.html"><code>Injector</code></a> for additional detail.
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## Simple Example
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Here is an example of a class that can be injected:
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```
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class Greeter {
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greet(name:string) {
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return 'Hello ' + name + '!';
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}
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}
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@Component({
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selector: 'greet',
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injectables: [
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Greeter
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]
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})
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@View({
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template: `{{greeter.greet('world')}}!`,
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directives: Child
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})
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class HelloWorld {
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greeter:Greeter;
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constructor(greeter:Greeter) {
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this.greeter = greeter;
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}
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}
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```
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@ -0,0 +1,518 @@
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p.location-badge.
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exported from <a href="/angular2/annotations.html">angular2/annotations</a>
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defined in <a href="https://github.com/angular/angular/tree/master/modules/angular2/src/core/annotations/annotations.js#L240">angular2/src/core/annotations/annotations.js (line 240)</a>
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:markdown
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Directives allow you to attach behavior to elements in the DOM.
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Directive is an abstract concept, instead use concrete directives: <a href="Component-class.html"><code>Component</code></a>, <a href="DynamicComponent-class.html"><code>DynamicComponent</code></a>, <a href="Decorator-class.html"><code>Decorator</code></a>
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or <a href="Viewport-class.html"><code>Viewport</code></a>.
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A directive consists of a single directive annotation and a controller class. When the directive's `selector` matches
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elements in the DOM, the following steps occur:
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1. For each directive, the `ElementInjector` attempts to resolve the directive's constructor arguments.
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2. Angular instantiates directives for each matched element using `ElementInjector` in a depth-first order,
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as declared in the HTML.
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## Understanding How Injection Works
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There are three stages of injection resolution.
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- *Pre-existing Injectors*:
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- The terminal <a href="../di/Injector-class.html"><code>Injector</code></a> cannot resolve dependencies. It either throws an error or, if the dependency was
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specified as `@Optional`, returns `null`.
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- The platform injector resolves browser singleton resources, such as: cookies, title, location, and others.
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- *Component Injectors*: Each `@Component` has its own <a href="../di/Injector-class.html"><code>Injector</code></a>, and they follow the same parent-child hierarchy
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as the components in the DOM.
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- *Element Injectors*: Each component has a Shadow DOM. Within the Shadow DOM each element has an `ElementInjector`
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which follow the same parent-child hierarchy as the DOM elements themselves.
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When a template is instantiated, it also must instantiate the corresponding directives in a depth-first order. The
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current `ElementInjector` resolves the constructor dependencies for each directive.
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Angular then resolves dependencies as follows, according to the order in which they appear in the <a href="View-class.html"><code>View</code></a>:
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1. Dependencies on the current element
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2. Dependencies on element injectors and their parents until it encounters a Shadow DOM boundary
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3. Dependencies on component injectors and their parents until it encounters the root component
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4. Dependencies on pre-existing injectors
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The `ElementInjector` can inject other directives, element-specific special objects, or it can delegate to the parent
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injector.
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To inject other directives, declare the constructor parameter as:
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- `directive:DirectiveType`: a directive on the current element only
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- `@Ancestor() directive:DirectiveType`: any directive that matches the type between the current element and the
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Shadow DOM root. Current element is not included in the resolution, therefore even if it could resolve it, it will
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be ignored.
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- `@Parent() directive:DirectiveType`: any directive that matches the type on a direct parent element only.
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- `@Children query:Query<DirectiveType>`: A live collection of direct child directives (will be implemented in later release).
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- `@Descendants query:Query<DirectiveType>`: A live collection of any child directives (will be implemented in later relaese).
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To inject element-specific special objects, declare the constructor parameter as:
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- `element: NgElement` to obtain a DOM element (DEPRECATED: replacement coming)
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- `viewContainer: ViewContainer` to control child template instantiation, for <a href="Viewport-class.html"><code>Viewport</code></a> directives only
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- `bindingPropagation: BindingPropagation` to control change detection in a more granular way.
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## Example
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The following example demonstrates how dependency injection resolves constructor arguments in practice.
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Assume this HTML template:
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```
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<div dependency="1">
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<div dependency="2">
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<div dependency="3" my-directive>
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<div dependency="4">
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<div dependency="5"></div>
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</div>
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<div dependency="6"></div>
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</div>
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</div>
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</div>
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```
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With the following `dependency` decorator and `SomeService` injectable class.
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```
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@Injectable()
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class SomeService {
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}
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@Decorator({
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selector: '[dependency]',
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properties: {
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'id':'dependency'
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}
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})
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class Dependency {
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id:string;
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}
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```
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Let's step through the different ways in which `MyDirective` could be declared...
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### No injection
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Here the constructor is declared with no arguments, therefore nothing is injected into `MyDirective`.
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```
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@Decorator({ selector: '[my-directive]' })
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class MyDirective {
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constructor() {
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}
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}
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```
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This directive would be instantiated with no dependencies.
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### Component-level injection
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Directives can inject any injectable instance from the closest component injector or any of its parents.
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Here, the constructor declares a parameter, `someService`, and injects the `SomeService` type from the parent
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component's injector.
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```
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@Decorator({ selector: '[my-directive]' })
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class MyDirective {
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constructor(someService: SomeService) {
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}
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}
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```
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This directive would be instantiated with a dependency on `SomeService`.
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### Injecting a directive from the current element
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Directives can inject other directives declared on the current element.
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```
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@Decorator({ selector: '[my-directive]' })
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class MyDirective {
|
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constructor(dependency: Dependency) {
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expect(dependency.id).toEqual(3);
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|
}
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}
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|
```
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This directive would be instantiated with `Dependency` declared at the same element, in this case `dependency="3"`.
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### Injecting a directive from a direct parent element
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Directives can inject other directives declared on a direct parent element. By definition, a directive with a
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`@Parent` annotation does not attempt to resolve dependencies for the current element, even if this would satisfy
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the dependency.
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```
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@Decorator({ selector: '[my-directive]' })
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class MyDirective {
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constructor(@Parent() dependency: Dependency) {
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expect(dependency.id).toEqual(2);
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}
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}
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```
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This directive would be instantiated with `Dependency` declared at the parent element, in this case `dependency="2"`.
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### Injecting a directive from any ancestor elements
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|
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Directives can inject other directives declared on any ancestor element (in the current Shadow DOM), i.e. on the
|
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parent element and its parents. By definition, a directive with an `@Ancestor` annotation does not attempt to
|
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resolve dependencies for the current element, even if this would satisfy the dependency.
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|
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|
```
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@Decorator({ selector: '[my-directive]' })
|
||||||
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class MyDirective {
|
||||||
|
constructor(@Ancestor() dependency: Dependency) {
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expect(dependency.id).toEqual(2);
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}
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}
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```
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Unlike the `@Parent` which only checks the parent, `@Ancestor` checks the parent, as well as its
|
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parents recursively. If `dependency="2"` didn't exist on the direct parent, this injection would have returned
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`dependency="1"`.
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|
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|
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### Injecting a live collection of direct child directives
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|
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||||||
|
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A directive can also query for other child directives. Since parent directives are instantiated before child
|
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|
directives, a directive can't simply inject the list of child directives. Instead, the directive
|
||||||
|
injects a <a href="../view/QueryList-class.html"><code>QueryList</code></a>, which updates its contents as children are added, removed, or moved by any
|
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<a href="Viewport-class.html"><code>Viewport</code></a> directive such as a `for`, an `if`, or a `switch`.
|
||||||
|
|
||||||
|
```
|
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|
@Decorator({ selector: '[my-directive]' })
|
||||||
|
class MyDirective {
|
||||||
|
constructor(@Query(Marker) dependencies:QueryList<Maker>) {
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
This directive would be instantiated with a <a href="../view/QueryList-class.html"><code>QueryList</code></a> which contains `Dependency` 4 and 6. Here, `Dependency`
|
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|
5 would not be included, because it is not a direct child.
|
||||||
|
|
||||||
|
### Injecting a live collection of descendant directives
|
||||||
|
|
||||||
|
Note: This is will be implemented in later release. ()
|
||||||
|
|
||||||
|
Similar to `@Children` above, but also includes the children of the child elements.
|
||||||
|
|
||||||
|
```
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@Decorator({ selector: '[my-directive]' })
|
||||||
|
class MyDirective {
|
||||||
|
constructor(@QueryDescendents(Marker) dependencies:QueryList<Maker>) {
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
This directive would be instantiated with a Query which would contain `Dependency` 4, 5 and 6.
|
||||||
|
|
||||||
|
### Optional injection
|
||||||
|
|
||||||
|
The normal behavior of directives is to return an error when a specified dependency cannot be resolved. If you
|
||||||
|
would like to inject `null` on unresolved dependency instead, you can annotate that dependency with `@Optional()`.
|
||||||
|
This explicitly permits the author of a template to treat some of the surrounding directives as optional.
|
||||||
|
|
||||||
|
```
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@Decorator({ selector: '[my-directive]' })
|
||||||
|
class MyDirective {
|
||||||
|
constructor(@Optional() dependency:Dependency) {
|
||||||
|
}
|
||||||
|
}
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||||||
|
```
|
||||||
|
|
||||||
|
This directive would be instantiated with a `Dependency` directive found on the current element. If none can be
|
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|
found, the injector supplies `null` instead of throwing an error.
|
||||||
|
|
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|
.l-main-section
|
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|
h2 Members
|
||||||
|
.l-sub-section
|
||||||
|
h3 constructor
|
||||||
|
|
||||||
|
|
||||||
|
pre.prettyprint
|
||||||
|
code.
|
||||||
|
constructor({
|
||||||
|
selector,
|
||||||
|
properties,
|
||||||
|
events,
|
||||||
|
hostListeners,
|
||||||
|
lifecycle
|
||||||
|
}:{
|
||||||
|
selector:string,
|
||||||
|
properties:any,
|
||||||
|
events:List,
|
||||||
|
hostListeners: any,
|
||||||
|
lifecycle:List
|
||||||
|
}={})
|
||||||
|
|
||||||
|
:markdown
|
||||||
|
|
||||||
|
|
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|
|
||||||
|
|
||||||
|
|
||||||
|
.l-sub-section
|
||||||
|
h3 events
|
||||||
|
|
||||||
|
|
||||||
|
:markdown
|
||||||
|
Enumerates the set of emitted events.
|
||||||
|
|
||||||
|
## Syntax
|
||||||
|
|
||||||
|
```
|
||||||
|
@Component({
|
||||||
|
events: ['statusChange']
|
||||||
|
})
|
||||||
|
class TaskComponent {
|
||||||
|
statusChange:EventEmitter;
|
||||||
|
|
||||||
|
constructor() {
|
||||||
|
this.statusChange = new EventEmitter();
|
||||||
|
}
|
||||||
|
|
||||||
|
onComplete() {
|
||||||
|
this.statusChange.next('completed');
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
.l-sub-section
|
||||||
|
h3 hasLifecycleHook
|
||||||
|
|
||||||
|
|
||||||
|
pre.prettyprint
|
||||||
|
code.
|
||||||
|
hasLifecycleHook(hook:string)
|
||||||
|
|
||||||
|
:markdown
|
||||||
|
Returns true if a directive participates in a given `LifecycleEvent`.
|
||||||
|
|
||||||
|
See <a href="onChange-var.html"><code>onChange</code></a>, <a href="onDestroy-var.html"><code>onDestroy</code></a>, <a href="onAllChangesDone-var.html"><code>onAllChangesDone</code></a> for details.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
.l-sub-section
|
||||||
|
h3 hostListeners
|
||||||
|
|
||||||
|
|
||||||
|
:markdown
|
||||||
|
Specifies which DOM hostListeners a directive listens to.
|
||||||
|
|
||||||
|
The `hostListeners` property defines a set of `event` to `method` key-value pairs:
|
||||||
|
|
||||||
|
- `event1`: the DOM event that the directive listens to.
|
||||||
|
- `statement`: the statement to execute when the event occurs.
|
||||||
|
If the evalutation of the statement returns `false`, then `preventDefault`is applied on the DOM event.
|
||||||
|
|
||||||
|
To listen to global events, a target must be added to the event name.
|
||||||
|
The target can be `window`, `document` or `body`.
|
||||||
|
|
||||||
|
When writing a directive event binding, you can also refer to the following local variables:
|
||||||
|
- `$event`: Current event object which triggered the event.
|
||||||
|
- `$target`: The source of the event. This will be either a DOM element or an Angular directive.
|
||||||
|
(will be implemented in later release)
|
||||||
|
|
||||||
|
|
||||||
|
## Syntax
|
||||||
|
|
||||||
|
```
|
||||||
|
@Directive({
|
||||||
|
hostListeners: {
|
||||||
|
'event1': 'onMethod1(arguments)',
|
||||||
|
'target:event2': 'onMethod2(arguments)',
|
||||||
|
...
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
## Basic Event Binding:
|
||||||
|
|
||||||
|
Suppose you want to write a directive that triggers on `change` events in the DOM and on `resize` events in window.
|
||||||
|
You would define the event binding as follows:
|
||||||
|
|
||||||
|
```
|
||||||
|
@Decorator({
|
||||||
|
selector: 'input',
|
||||||
|
hostListeners: {
|
||||||
|
'change': 'onChange($event)',
|
||||||
|
'window:resize': 'onResize($event)'
|
||||||
|
}
|
||||||
|
})
|
||||||
|
class InputDecorator {
|
||||||
|
onChange(event:Event) {
|
||||||
|
}
|
||||||
|
onResize(event:Event) {
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
Here the `onChange` method of `InputDecorator` is invoked whenever the DOM element fires the 'change' event.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
.l-sub-section
|
||||||
|
h3 lifecycle
|
||||||
|
|
||||||
|
|
||||||
|
:markdown
|
||||||
|
Specifies a set of lifecycle hostListeners in which the directive participates.
|
||||||
|
|
||||||
|
See <a href="onChange-var.html"><code>onChange</code></a>, <a href="onDestroy-var.html"><code>onDestroy</code></a>, <a href="onAllChangesDone-var.html"><code>onAllChangesDone</code></a> for details.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
.l-sub-section
|
||||||
|
h3 properties
|
||||||
|
|
||||||
|
|
||||||
|
:markdown
|
||||||
|
Enumerates the set of properties that accept data binding for a directive.
|
||||||
|
|
||||||
|
The `properties` property defines a set of `directiveProperty` to `bindingProperty`
|
||||||
|
key-value pairs:
|
||||||
|
|
||||||
|
- `directiveProperty` specifies the component property where the value is written.
|
||||||
|
- `bindingProperty` specifies the DOM property where the value is read from.
|
||||||
|
|
||||||
|
You can include a <a href="../pipes/Pipe-class.html"><code>Pipe</code></a> when specifying a `bindingProperty` to allow for data transformation and structural
|
||||||
|
change detection of the value. These pipes will be evaluated in the context of this component.
|
||||||
|
|
||||||
|
|
||||||
|
## Syntax
|
||||||
|
|
||||||
|
```
|
||||||
|
@Directive({
|
||||||
|
properties: {
|
||||||
|
'directiveProperty1': 'bindingProperty1',
|
||||||
|
'directiveProperty2': 'bindingProperty2 | pipe1 | ...',
|
||||||
|
...
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
|
||||||
|
## Basic Property Binding
|
||||||
|
|
||||||
|
We can easily build a simple `Tooltip` directive that exposes a `tooltip` property, which can be used in templates
|
||||||
|
with standard Angular syntax. For example:
|
||||||
|
|
||||||
|
```
|
||||||
|
@Decorator({
|
||||||
|
selector: '[tooltip]',
|
||||||
|
properties: {
|
||||||
|
'text': 'tooltip'
|
||||||
|
}
|
||||||
|
})
|
||||||
|
class Tooltip {
|
||||||
|
set text(text) {
|
||||||
|
// This will get called every time the 'tooltip' binding changes with the new value.
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
We can then bind to the `tooltip' property as either an expression (`someExpression`) or as a string literal, as
|
||||||
|
shown in the HTML template below:
|
||||||
|
|
||||||
|
```html
|
||||||
|
<div [tooltip]="someExpression">...</div>
|
||||||
|
<div tooltip="Some Text">...</div>
|
||||||
|
```
|
||||||
|
|
||||||
|
Whenever the `someExpression` expression changes, the `properties` declaration instructs
|
||||||
|
Angular to update the `Tooltip`'s `text` property.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
## Bindings With Pipes
|
||||||
|
|
||||||
|
You can also use pipes when writing binding definitions for a directive.
|
||||||
|
|
||||||
|
For example, we could write a binding that updates the directive on structural changes, rather than on reference
|
||||||
|
changes, as normally occurs in change detection.
|
||||||
|
|
||||||
|
See <a href="../pipes/Pipe-class.html"><code>Pipe</code></a> and <a href="../pipes/keyValDiff-var.html"><code>keyValDiff</code></a> documentation for more details.
|
||||||
|
|
||||||
|
```
|
||||||
|
@Decorator({
|
||||||
|
selector: '[class-set]',
|
||||||
|
properties: {
|
||||||
|
'classChanges': 'classSet | keyValDiff'
|
||||||
|
}
|
||||||
|
})
|
||||||
|
class ClassSet {
|
||||||
|
set classChanges(changes:KeyValueChanges) {
|
||||||
|
// This will get called every time the `class-set` expressions changes its structure.
|
||||||
|
}
|
||||||
|
}
|
||||||
|
```
|
||||||
|
|
||||||
|
The template that this directive is used in may also contain its own pipes. For example:
|
||||||
|
|
||||||
|
```html
|
||||||
|
<div [class-set]="someExpression | somePipe">
|
||||||
|
```
|
||||||
|
|
||||||
|
In this case, the two pipes compose as if they were inlined: `someExpression | somePipe | keyValDiff`.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
.l-sub-section
|
||||||
|
h3 selector
|
||||||
|
|
||||||
|
|
||||||
|
:markdown
|
||||||
|
The CSS selector that triggers the instantiation of a directive.
|
||||||
|
|
||||||
|
Angular only allows directives to trigger on CSS selectors that do not cross element boundaries.
|
||||||
|
|
||||||
|
`selector` may be declared as one of the following:
|
||||||
|
|
||||||
|
- `element-name`: select by element name.
|
||||||
|
- `.class`: select by class name.
|
||||||
|
- `[attribute]`: select by attribute name.
|
||||||
|
- `[attribute=value]`: select by attribute name and value.
|
||||||
|
- `:not(sub_selector)`: select only if the element does not match the `sub_selector`.
|
||||||
|
- `selector1, selector2`: select if either `selector1` or `selector2` matches.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
Suppose we have a directive with an `input[type=text]` selector.
|
||||||
|
|
||||||
|
And the following HTML:
|
||||||
|
|
||||||
|
```html
|
||||||
|
<form>
|
||||||
|
<input type="text">
|
||||||
|
<input type="radio">
|
||||||
|
<form>
|
||||||
|
```
|
||||||
|
|
||||||
|
The directive would only be instantiated on the `<input type="text">` element.
|
||||||
|
|
||||||
|
|
||||||
|
|
||||||
|
|
Loading…
Reference in New Issue