Cheat Sheet

速查表

Bootstrapping 引导/启动

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

platformBrowserDynamic().bootstrapModule(AppModule);

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

用 NgModule 中指定的根组件进行启动。
NgModules

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

@NgModule({ declarations: ..., imports: ...,
exports: ..., providers: ..., bootstrap: ...})
class MyModule {}

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

定义一个模块，其中可以包含组件、指令、管道和服务提供商。
declarations: [MyRedComponent, MyBlueComponent, MyDatePipe]

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

属于当前模块的组件、指令和管道的列表。
imports: [BrowserModule, SomeOtherModule]

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

本模块所导入的模块列表
exports: [MyRedComponent, MyDatePipe]

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

那些导入了本模块的模块所能看到的组件、指令和管道的列表
providers: [MyService, { provide: ... }]

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

依赖注入提供商的列表，本模块以及本模块导入的所有模块中的内容都可以看见它们。
bootstrap: [MyAppComponent]

List of components to bootstrap when this module is bootstrapped.

当本模块启动时，随之启动的组件列表。
Template syntax 模板语法
<input [value]="firstName">

Binds property value to the result of expression firstName.

把value属性绑定到表达式firstName
<div [attr.role]="myAriaRole">

Binds attribute role to the result of expression myAriaRole.

把属性（Attribute）role绑定到表达式myAriaRole的结果。
<div [class.extra-sparkle]="isDelightful">

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

根据isDelightful表达式的结果是否为真，决定CSS类extra-sparkle是否出现在当前元素上。
<div [style.width.px]="mySize">

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

把CSS样式属性width的px（像素）值绑定到表达式mySize的结果。单位是可选的。
<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.

当这个按钮元素（及其子元素）上的click事件触发时，调用方法readRainbow，并把这个事件对象作为参数传进去。
<div title="Hello {{ponyName}}">

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

把一个属性绑定到插值字符串（如"Hello Seabiscuit"）。这种写法等价于<div [title]="'Hello ' + ponyName">
<p>Hello {{ponyName}}</p>

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

把文本内容绑定到插值字符串（如"Hello Seabiscuit"）
<my-cmp [(title)]="name">

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

设置双向绑定。等价于<my-cmp [title]="name" (titleChange)="name=$event">。
<video #movieplayer ...>
<button (click)="movieplayer.play()">
</video>

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

创建一个局部变量movieplayer，支持在当前模板的数据绑定和事件绑定表达式中访问video元素的实例。
<p *myUnless="myExpression">...</p>

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

这个 * 符号会把当前元素转换成一个内嵌的模板。它等价于： <ng-template [myUnless]="myExpression"><p>...</p></ng-template>
<p>Card No.: {{cardNumber | myCardNumberFormatter}}</p>

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

使用名叫myCardNumberFormatter的管道对表达式cardNumber的当前值进行变幻
<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.

安全导航操作符（?）表示employer字段是可选的，如果它是 undefined ，那么表达式其余的部分就会被忽略，并返回 undefined。
<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.

模板中的 SVG 片段需要给它的根元素加上svg:前缀，以便把 SVG 元素和 HTML 元素区分开。
<svg>
<rect x="0" y="0" width="100" height="100"/>
</svg>

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

以<svg>作为根元素时会自动识别为 SVG 元素，不需要前缀。
Built-in directives 内置指令

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

<section *ngIf="showSection">

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

根据showSection表达式的结果，移除或重新创建 DOM 树的一部分。
<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.

把li元素及其内容变成一个模板，并使用这个模板为列表中的每一个条目实例化一个视图。
<div [ngSwitch]="conditionExpression">
<ng-template [ngSwitchCase]="case1Exp">...</ng-template>
<ng-template ngSwitchCase="case2LiteralString">...</ng-template>
<ng-template ngSwitchDefault>...</ng-template>
</div>

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

根据conditionExpression的当前值选择一个嵌入式模板，并用它替换这个 div 的内容。
<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.

根据 map 中的 value 是否为真，来决定该元素上是否出现与 name 对应的 CSS 类。右侧的表达式应该返回一个形如 {class-name: true/false} 的 map。
<div [ngStyle]="{'property': 'value'}">
<div [ngStyle]="dynamicStyles()">

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.

允许你使用 CSS 为 HTML 元素指定样式。你可以像第一个例子那样直接使用 CSS，也可以调用组件中的方法。
Forms 表单

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

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

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

为表单控件提供双向数据绑定、解析和验证功能。
Class decorators 类装饰器

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

@Component({...})
class MyComponent() {}

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

声明一个类是组件，并提供该组件的元数据。
@Directive({...})
class MyDirective() {}

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

声明一个类是指令，并提供该指令的元数据。
@Pipe({...})
class MyPipe() {}

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

声明一个类是管道，并提供该管道的元数据。
@Injectable()
class MyService() {}

Declares that a class has dependencies that should be injected into the constructor when the dependency injector is creating an instance of this class.

声明某个类具有一些依赖。当依赖注入器要创建这个类的实例时，应该把这些依赖注入到它的构造函数中。
Directive configuration 指令配置项

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

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

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

指定一个 CSS 选择器，用于在模板中标记出该指令。支持的选择器类型包括：元素名、[属性名], .类名 和 :not()。

Does not support parent-child relationship selectors.

但不支持指定父子关系的选择器。
providers: [MyService, { provide: ... }]

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

该指令及其子指令的依赖注入提供商列表。
Component configuration 组件配置项

@Component extends @Directive, so the @Directive configuration applies to components as well

@Component 继承自 @Directive， 因此，@Directive 的这些配置项也同样适用于组件。
moduleId: module.id

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

如果设置了，那么 templateUrl 和 styleUrl 的路径就会相对于当前组件进行解析。
viewProviders: [MyService, { provide: ... }]

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

依赖注入提供商列表，但它们的范围被限定为当前组件的视图。
template: 'Hello {{name}}'
templateUrl: 'my-component.html'

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

当前组件视图的内联模板或外部模板的 URL 。
styles: ['.primary {color: red}']
styleUrls: ['my-component.css']

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

用于为当前组件的视图提供样式的内联 CSS 或外部样式表 URL 的列表。
Class field decorators for directives and components 给指令和组件使用的类属性配置项

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

@Input() myProperty;

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

声明一个输入属性，你可以通过属性绑定来更新它，如 <my-cmp [myProperty]="someExpression">。

@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()">).

声明一个输出属性，它发出事件，你可以用事件绑定来订阅它们（如：<my-cmp (myEvent)="doSomething()">）。
@HostBinding('class.valid') isValid;

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

把宿主元素的一个属性（这里是 CSS 类 valid）绑定到指令或组件上的 isValid 属性。
@HostListener('click', ['$event']) onClick(e) {...}

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

用指令或组件上的onClick方法订阅宿主元素上的click事件，并从中获取$event参数（可选）
@ContentChild(myPredicate) myChildComponent;

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

把组件内容查询（myPredicate）的第一个结果绑定到该类的 myChildComponent 属性上。
@ContentChildren(myPredicate) myChildComponents;

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

把组件内容查询（myPredicate）的全部结果绑定到该类的 myChildComponents 属性上
@ViewChild(myPredicate) myChildComponent;

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

把组件视图查询（myPredicate）的第一个结果绑定到该类的 myChildComponent 属性上。对指令无效。
@ViewChildren(myPredicate) myChildComponents;

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

把组件视图查询（myPredicate）的全部结果绑定到该类的 myChildComponents 属性上。对指令无效。
Directive and component change detection and lifecycle hooks 指令与组件的变更检测与生命周期钩子

(implemented as class methods)

由类的方法实现。
constructor(myService: MyService, ...) { ... }

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

在任何其它生命周期钩子之前调用。可以用它来注入依赖项，但不要在这里做正事。
ngOnChanges(changeRecord) { ... }

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

每当输入属性发生变化时就会调用，但位于处理内容（ng-content）或子视图之前。
ngOnInit() { ... }

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

在调用完构造函数、初始化完所有输入属性并首次调用过ngOnChanges之后调用。
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.

每当对组件或指令的输入属性进行变更检测时就会调用。可以用它来扩展变更检测逻辑，执行自定义的检测逻辑。
ngAfterContentInit() { ... }

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

ngOnInit完成之后，当组件或指令的内容（ng-content）已经初始化完毕时调用。
ngAfterContentChecked() { ... }

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

每当组件或指令的内容（ng-content）做变更检测时调用。
ngAfterViewInit() { ... }

Called after ngAfterContentInit when the component's view has been initialized. Applies to components only.

当ngAfterContentInit完毕，并且组件的视图已经初始化完毕时调用。只适用于组件。
ngAfterViewChecked() { ... }

Called after every check of the component's view. Applies to components only.

当组件视图每次执行变更检测时调用。只适用于组件。
ngOnDestroy() { ... }

Called once, before the instance is destroyed.

只在实例被销毁前调用一次。
Dependency injection configuration 依赖注入配置项
{ provide: MyService, useClass: MyMockService }

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

把 MyService 的服务提供商设置或改写为 MyMockService 类。
{ provide: MyService, useFactory: myFactory }

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

把 MyService 的服务提供商设置或改写为 myFactory 工厂函数。
{ provide: MyValue, useValue: 41 }

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

把 MyValue 的服务提供商改写为一个特定的值 41 。
Routing and navigation 路由与导航

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

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

const routing = RouterModule.forRoot(routes);

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

为该应用配置路由。支持静态、参数化、重定向和通配符路由。也支持自定义路由数据和解析（resolve）函数。

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

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

标记出一个位置，用来加载活动路由的组件。

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

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.

使用路由体系创建一个到其它视图的链接。路由体系由路由路径、必要参数、可选参数、查询参数和文档片段组成。要导航到根路由，请使用/前缀；要导航到子路由，使用./前缀；要导航到兄弟路由或父级路由，使用../前缀。
<a [routerLink]="[ '/path' ]" routerLinkActive="active">

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

当 routerLink 指向的路由变成活动路由时，为当前元素添加一些类（比如这里的 active）。
class CanActivateGuard implements CanActivate {
canActivate(
route: ActivatedRouteSnapshot,
state: RouterStateSnapshot
): Observable<boolean>|Promise<boolean>|boolean { ... }
}

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

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

用来定义类的接口。路由器会首先调用本接口来决定是否激活该路由。应该返回一个 boolean 或能解析成 boolean 的 Observable/Promise。
class CanDeactivateGuard implements CanDeactivate<T> {
canDeactivate(
component: T,
route: ActivatedRouteSnapshot,
state: RouterStateSnapshot
): Observable<boolean>|Promise<boolean>|boolean { ... }
}

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

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 or an Observable/Promise that resolves to a boolean.

用来定义类的接口。路由器会在导航离开前首先调用本接口以决定是否取消激活本路由。应该返回一个 boolean 或能解析成 boolean 的 Observable/Promise。
class CanActivateChildGuard implements CanActivateChild {
canActivateChild(
route: ActivatedRouteSnapshot,
state: RouterStateSnapshot
): Observable<boolean>|Promise<boolean>|boolean { ... }
}

{ path: ..., canActivateChild: [CanActivateGuard],
children: ... }

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 or an Observable/Promise that resolves to a boolean.

用来定义类的接口。路由器会首先调用本接口来决定是否激活一个子路由。应该返回一个 boolean 或能解析成 boolean 的 Observable/Promise。
class ResolveGuard implements Resolve<T> {
resolve(
route: ActivatedRouteSnapshot,
state: RouterStateSnapshot
): Observable<any>|Promise<any>|any { ... }
}

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

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.

用来定义类的接口。路由器会在渲染该路由之前，首先调用它来解析路由数据。应该返回一个值或能解析成值的 Observable/Promise。
class CanLoadGuard implements CanLoad {
canLoad(
route: Route
): Observable<boolean>|Promise<boolean>|boolean { ... }
}

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

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 or an Observable/Promise that resolves to a boolean.

用来定义类的接口。路由器会首先调用它来决定是否应该加载一个惰性加载模块。应该返回一个 boolean 或能解析成 boolean 的 Observable/Promise。