{ "id": "guide/cheatsheet", "title": "Cheat Sheet", "contents": "\n\n\n
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Cheat Sheetlink

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Bootstrapping

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';\n

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platformBrowserDynamic().bootstrapModule(AppModule);

Bootstraps the app, using the root component from the specified NgModule.

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NgModules

import { NgModule } from '@angular/core';\n

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@NgModule({\n declarations: ..., imports: ..., exports: ...,\n providers: ..., bootstrap: ...\n})\nclass MyModule {}\n

Defines a module that contains components, directives, pipes, and providers.

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declarations: [MyRedComponent, MyBlueComponent, MyDatePipe]

List of components, directives, and pipes that belong to this module.

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imports: [BrowserModule, SomeOtherModule]

List of modules to import into this module. Everything from the imported modules\nis available to declarations of this module.

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exports: [MyRedComponent, MyDatePipe]

List of components, directives, and pipes visible to modules that import this module.

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providers: [MyService, { provide: ... }]

List of dependency injection providers visible both to the contents of this module and to importers of this module.

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entryComponents: [SomeComponent, OtherComponent]

List of components not referenced in any reachable template, for example dynamically created from code.

bootstrap: [MyAppComponent]

List of components to bootstrap when this module is bootstrapped.

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Template syntax
<input [value]=\"firstName\">

Binds property value to the result of expression firstName.

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<div [attr.role]=\"myAriaRole\">

Binds attribute role to the result of expression myAriaRole.

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<div [class.extra-sparkle]=\"isDelightful\">

Binds the presence of the CSS class extra-sparkle on the element to the truthiness of the expression isDelightful.

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<div [style.width.px]=\"mySize\">

Binds style property width to the result of expression mySize in pixels. Units are optional.

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<button (click)=\"readRainbow($event)\">

Calls method readRainbow when a click event is triggered on this button element (or its children) and passes in the event object.

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<div title=\"Hello {{ponyName}}\">

Binds a property to an interpolated string, for example, \"Hello Seabiscuit\". Equivalent to:\n<div [title]=\"'Hello ' + ponyName\">

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<p>Hello {{ponyName}}</p>

Binds text content to an interpolated string, for example, \"Hello Seabiscuit\".

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<my-cmp [(title)]=\"name\">

Sets up two-way data binding. Equivalent to: <my-cmp [title]=\"name\" (titleChange)=\"name=$event\">

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<video #movieplayer ...></video>\n<button (click)=\"movieplayer.play()\">Play</button>\n

Creates a local variable movieplayer that provides access to the video element instance in data-binding and event-binding expressions in the current template.

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<p *myUnless=\"myExpression\">...</p>

The * symbol turns the current element into an embedded template. Equivalent to:\n<ng-template [myUnless]=\"myExpression\"><p>...</p></ng-template>

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<p>Card No.: {{cardNumber | myCardNumberFormatter}}</p>

Transforms the current value of expression cardNumber via the pipe called myCardNumberFormatter.

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<p>Employer: {{employer?.companyName}}</p>

The safe navigation operator (?) means that the employer field is optional and if undefined, the rest of the expression should be ignored.

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<svg:rect x=\"0\" y=\"0\" width=\"100\" height=\"100\"/>

An SVG snippet template needs an svg: prefix on its root element to disambiguate the SVG element from an HTML component.

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<svg>\n <rect x=\"0\" y=\"0\" width=\"100\" height=\"100\"/>\n</svg>\n

An <svg> root element is detected as an SVG element automatically, without the prefix.

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Built-in directives

import { CommonModule } from '@angular/common';\n

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<section *ngIf=\"showSection\">

Removes or recreates a portion of the DOM tree based on the showSection expression.

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<li *ngFor=\"let item of list\">

Turns the li element and its contents into a template, and uses that to instantiate a view for each item in list.

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<div [ngSwitch]=\"conditionExpression\">\n <ng-template [ngSwitchCase]=\"case1Exp\">...</ng-template>\n <ng-template ngSwitchCase=\"case2LiteralString\">...</ng-template>\n <ng-template ngSwitchDefault>...</ng-template>\n</div>\n

Conditionally swaps the contents of the div by selecting one of the embedded templates based on the current value of conditionExpression.

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<div [ngClass]=\"{'active': isActive, 'disabled': isDisabled}\">

Binds the presence of CSS classes on the element to the truthiness of the associated map values. The right-hand expression should return {class-name: true/false} map.

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<div [ngStyle]=\"{'property': 'value'}\">\n<div [ngStyle]=\"dynamicStyles()\">\n

Allows you to assign styles to an HTML element using CSS. You can use CSS directly, as in the first example, or you can call a method from the component.

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Forms

import { FormsModule } from '@angular/forms';\n

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<input [(ngModel)]=\"userName\">

Provides two-way data-binding, parsing, and validation for form controls.

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Class decorators

import { Directive, ... } from '@angular/core';\n

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@Component({...})\nclass MyComponent() {}\n

Declares that a class is a component and provides metadata about the component.

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@Directive({...})\nclass MyDirective() {}\n

Declares that a class is a directive and provides metadata about the directive.

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@Pipe({...})\nclass MyPipe() {}\n

Declares that a class is a pipe and provides metadata about the pipe.

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@Injectable()\nclass MyService() {}\n

Declares that a class can be provided and injected by other classes. Without this decorator, the compiler won't generate enough metadata to allow the class to be created properly when it's injected somewhere.

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Directive configuration

@Directive({ property1: value1, ... })\n

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selector: '.cool-button:not(a)'

Specifies a CSS selector that identifies this directive within a template. Supported selectors include element,\n[attribute], .class, and :not().

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Does not support parent-child relationship selectors.

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providers: [MyService, { provide: ... }]

List of dependency injection providers for this directive and its children.

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Component configuration

\n@Component extends @Directive,\nso the @Directive configuration applies to components as well

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moduleId: module.id

If set, the templateUrl and styleUrl are resolved relative to the component.

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viewProviders: [MyService, { provide: ... }]

List of dependency injection providers scoped to this component's view.

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template: 'Hello {{name}}'\ntemplateUrl: 'my-component.html'\n

Inline template or external template URL of the component's view.

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styles: ['.primary {color: red}']\nstyleUrls: ['my-component.css']\n

List of inline CSS styles or external stylesheet URLs for styling the component’s view.

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Class field decorators for directives and components

import { Input, ... } from '@angular/core';\n

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@Input() myProperty;

Declares an input property that you can update via property binding (example:\n<my-cmp [myProperty]=\"someExpression\">).

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@Output() myEvent = new EventEmitter();

Declares an output property that fires events that you can subscribe to with an event binding (example: <my-cmp (myEvent)=\"doSomething()\">).

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@HostBinding('class.valid') isValid;

Binds a host element property (here, the CSS class valid) to a directive/component property (isValid).

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@HostListener('click', ['$event']) onClick(e) {...}

Subscribes to a host element event (click) with a directive/component method (onClick), optionally passing an argument ($event).

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@ContentChild(myPredicate) myChildComponent;

Binds the first result of the component content query (myPredicate) to a property (myChildComponent) of the class.

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@ContentChildren(myPredicate) myChildComponents;

Binds the results of the component content query (myPredicate) to a property (myChildComponents) of the class.

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@ViewChild(myPredicate) myChildComponent;

Binds the first result of the component view query (myPredicate) to a property (myChildComponent) of the class. Not available for directives.

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@ViewChildren(myPredicate) myChildComponents;

Binds the results of the component view query (myPredicate) to a property (myChildComponents) of the class. Not available for directives.

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Directive and component change detection and lifecycle hooks

(implemented as class methods)\n

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constructor(myService: MyService, ...) { ... }

Called before any other lifecycle hook. Use it to inject dependencies, but avoid any serious work here.

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ngOnChanges(changeRecord) { ... }

Called after every change to input properties and before processing content or child views.

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ngOnInit() { ... }

Called after the constructor, initializing input properties, and the first call to ngOnChanges.

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ngDoCheck() { ... }

Called every time that the input properties of a component or a directive are checked. Use it to extend change detection by performing a custom check.

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ngAfterContentInit() { ... }

Called after ngOnInit when the component's or directive's content has been initialized.

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ngAfterContentChecked() { ... }

Called after every check of the component's or directive's content.

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ngAfterViewInit() { ... }

Called after ngAfterContentInit when the component's views and child views / the view that a directive is in has been initialized.

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ngAfterViewChecked() { ... }

Called after every check of the component's views and child views / the view that a directive is in.

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ngOnDestroy() { ... }

Called once, before the instance is destroyed.

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Dependency injection configuration
{ provide: MyService, useClass: MyMockService }

Sets or overrides the provider for MyService to the MyMockService class.

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{ provide: MyService, useFactory: myFactory }

Sets or overrides the provider for MyService to the myFactory factory function.

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{ provide: MyValue, useValue: 41 }

Sets or overrides the provider for MyValue to the value 41.

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Routing and navigation

import { Routes, RouterModule, ... } from '@angular/router';\n

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const routes: Routes = [\n { path: '', component: HomeComponent },\n { path: 'path/:routeParam', component: MyComponent },\n { path: 'staticPath', component: ... },\n { path: '**', component: ... },\n { path: 'oldPath', redirectTo: '/staticPath' },\n { path: ..., component: ..., data: { message: 'Custom' } }\n]);\n

const routing = RouterModule.forRoot(routes);\n

Configures routes for the application. Supports static, parameterized, redirect, and wildcard routes. Also supports custom route data and resolve.

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<router-outlet></router-outlet>\n<router-outlet name=\"aux\"></router-outlet>\n

Marks the location to load the component of the active route.

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<a routerLink=\"/path\">\n<a [routerLink]=\"[ '/path', routeParam ]\">\n<a [routerLink]=\"[ '/path', { matrixParam: 'value' } ]\">\n<a [routerLink]=\"[ '/path' ]\" [queryParams]=\"{ page: 1 }\">\n<a [routerLink]=\"[ '/path' ]\" fragment=\"anchor\">\n

Creates a link to a different view based on a route instruction consisting of a route path, required and optional parameters, query parameters, and a fragment. To navigate to a root route, use the / prefix; for a child route, use the ./prefix; for a sibling or parent, use the ../ prefix.

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<a [routerLink]=\"[ '/path' ]\" routerLinkActive=\"active\">

The provided classes are added to the element when the routerLink becomes the current active route.

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class CanActivateGuard implements CanActivate {\n canActivate(\n route: ActivatedRouteSnapshot,\n state: RouterStateSnapshot\n ): Observable<boolean|UrlTree>|Promise<boolean|UrlTree>|boolean|UrlTree { ... }\n}\n

{ path: ..., canActivate: [CanActivateGuard] }\n

An interface for defining a class that the router should call first to determine if it should activate this component. Should return a boolean|UrlTree or an Observable/Promise that resolves to a boolean|UrlTree.

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class CanDeactivateGuard implements CanDeactivate<T> {\n canDeactivate(\n component: T,\n route: ActivatedRouteSnapshot,\n state: RouterStateSnapshot\n ): Observable<boolean|UrlTree>|Promise<boolean|UrlTree>|boolean|UrlTree { ... }\n}\n

{ path: ..., canDeactivate: [CanDeactivateGuard] }\n

An interface for defining a class that the router should call first to determine if it should deactivate this component after a navigation. Should return a boolean|UrlTree or an Observable/Promise that resolves to a boolean|UrlTree.

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class CanActivateChildGuard implements CanActivateChild {\n canActivateChild(\n route: ActivatedRouteSnapshot,\n state: RouterStateSnapshot\n ): Observable<boolean|UrlTree>|Promise<boolean|UrlTree>|boolean|UrlTree { ... }\n}\n

{ path: ..., canActivateChild: [CanActivateGuard],\nchildren: ... }\n

An interface for defining a class that the router should call first to determine if it should activate the child route. Should return a boolean|UrlTree or an Observable/Promise that resolves to a boolean|UrlTree.

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class ResolveGuard implements Resolve<T> {\n resolve(\n route: ActivatedRouteSnapshot,\n state: RouterStateSnapshot\n ): Observable<any>|Promise<any>|any { ... }\n}\n

{ path: ..., resolve: [ResolveGuard] }\n

An interface for defining a class that the router should call first to resolve route data before rendering the route. Should return a value or an Observable/Promise that resolves to a value.

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class CanLoadGuard implements CanLoad {\n canLoad(\n route: Route\n ): Observable<boolean|UrlTree>|Promise<boolean|UrlTree>|boolean|UrlTree { ... }\n}\n

{ path: ..., canLoad: [CanLoadGuard], loadChildren: ... }\n

An interface for defining a class that the router should call first to check if the lazy loaded module should be loaded. Should return a boolean|UrlTree or an Observable/Promise that resolves to a boolean|UrlTree.

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