Angular 词汇表
Glossary
Angular 有自己的词汇表。 虽然大多数 Angular 短语都是日常用语或计算机术语，但是在 Angular 体系中，它们有特别的含义。
Angular has its own vocabulary. Most Angular terms are common English words or computing terms that have a specific meaning within the Angular system.
本词汇表列出了常用术语和少量具有反常或意外含义的不常用术语。
This glossary lists the most prominent terms and a few less familiar ones with unusual or unexpected definitions.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
预 (ahead-of-time, AOT) 编译
ahead-of-time (AOT) compilation
Angular 的预先（AOT）编译器可以在编译期间把 Angular 的 HTML 代码和 TypeScript 代码转换成高效的 JavaScript 代码，这样浏览器就可以直接下载并运行它们。 对于产品环境，这是最好的编译模式，相对于即时 (JIT) 编译而言，它能减小加载时间，并提高性能。
The Angular ahead-of-time (AOT) compiler converts Angular HTML and TypeScript code into efficient JavaScript code during the build phase, before the browser downloads and runs that code. This is the best compilation mode for production environments, with decreased load time and increased performance compared to just-in-time (JIT) compilation.
使用命令行工具 ngc 来编译你的应用之后，就可以直接启动一个模块工厂，这意味着你不必再在 JavaScript 打包文件中包含 Angular 编译器。
By compiling your application using the ngc command-line tool, you can bootstrap directly to a module factory, so you don't need to include the Angular compiler in your JavaScript bundle.
Angular 元素（element）
Angular element
An Angular component packaged as a custom element.
参见 Angular 元素 一文。
Learn more in Angular Elements Overview.
注解（Annotation）
Annotation
一种为类提供元数据的结构。参见 装饰器。
A structure that provides metadata for a class. See decorator.
应用外壳（app-shell）
app-shell
应用外壳是一种在构建期间通过路由为应用渲染出部分内容的方式。 这样就能为用户快速呈现出一个有意义的首屏页面，因为浏览器可以在初始化脚本之前渲染出静态的 HTML 和 CSS。
App shell is a way to render a portion of your application via a route at build time. This gives users a meaningful first paint of your application that appears quickly because the browser can render static HTML and CSS without the need to initialize JavaScript.
欲知详情，参见应用外壳模型。
Learn more in The App Shell Model.
你可以使用 Angular CLI 来生成一个应用外壳。 它可以在浏览器下载完整版应用之前，先快速启动一个静态渲染页面（所有页面的公共骨架）来增强用户体验，等代码加载完毕后再自动切换到完整版。
You can use the Angular CLI to generate an app shell. This can improve the user experience by quickly launching a static rendered page (a skeleton common to all pages) while the browser downloads the full client version and switches to it automatically after the code loads.
See also Service Worker and PWA.
建筑师（Architect）
Architect
CLI 用来根据所提供的配置执行复杂任务（比如编译和执行测试）的工具。 建筑师是一个外壳，它用来对一个指定的目标配置来执行一个构建器（builder） (定义在一个 npm 包中)。
The tool that the CLI uses to perform complex tasks such as compilation and test running, according to a provided configuration. Architect is a shell that runs a builder (defined in an npm package) with a given target configuration.
在工作空间配置文件中，"architect" 区可以为建筑师的各个构建器提供配置项。
In the workspace configuration file, an "architect" section provides configuration options for Architect builders.
比如，内置的 linting 构建器定义在 @angular-devkit/build_angular:tslint 包中，它使用 TSLint 工具来执行 linting 操作，其配置是在 tslint.json 文件中指定的。
For example, a built-in builder for linting is defined in the package @angular-devkit/build_angular:tslint, which uses the TSLint tool to perform linting, with a configuration specified in a tslint.json file.
使用 CLI 命令 ng run可以通过指定与某个构建器相关联的目标配置来调用此构建器。 整合器（Integrator）可以添加一些构建器来启用某些工具和工作流，以便通过 Angular CLI 来运行它。比如，自定义构建器可以把 CLI 命令（如 ng build 或 ng test）的内置实现替换为第三方工具。
Use the CLI command ng runto invoke a builder by specifying a target configuration associated with that builder. Integrators can add builders to enable tools and workflows to run through the Angular CLI. For example, a custom builder can replace the third-party tools used by the built-in implementations for CLI commands such as ng build or ng test.
属性型指令（attribute directives）
attribute directives
指令 (directive)的一种。可以监听或修改其它 HTML 元素、特性 (attribute)、属性 (property)、组件的行为。通常用作 HTML 属性，就像它的名字所暗示的那样。
A category of directive that can listen to and modify the behavior of other HTML elements, attributes, properties, and components. They are usually represented as HTML attributes, hence the name.
要了解更多，参见属性型指令
Learn more in Attribute Directives.
绑定 (binding)
binding
广义上是指把变量或属性设置为某个数据值的一种实践。 在 Angular 中，一般是指数据绑定，它会根据数据对象属性的值来设置 DOM 对象的属性。
Generally, the practice of setting a variable or property to a data value. Within Angular, typically refers to data binding, which coordinates DOM object properties with data object properties.
有时也会指在“令牌（Token）”和依赖提供者（Provider） 之间的依赖注入 绑定。
Sometimes refers to a dependency-injection binding between a token and a dependency provider.
启动/引导 (bootstrap)
bootstrap
一种用来初始化和启动应用或系统的途径。
A way to initialize and launch an app or system.
在 Angular 中，应用的根模块（AppModule）有一个 bootstrap 属性，用于指出该应用的的顶层组件。 在引导期间，Angular 会创建这些组件，并插入到宿主页面 index.html 中。 你可以在同一个 index.html 中引导多个应用，每个应用都有一些自己的组件。
In Angular, an app's root NgModule (AppModule) has a bootstrap property that identifies the app's top-level components. During the bootstrap process, Angular creates and inserts these components into the index.html host web page. You can bootstrap multiple apps in the same index.html. Each app contains its own components.
要了解更多，参见引导一章。
Learn more in Bootstrapping.
构建器（Builder）
builder
一个函数，它使用 Architect API 来执行复杂的过程，比如构建或测试。 构建器的代码定义在一个 npm 包中。
A function that uses the Architect API to perform a complex process such as "build" or "test". The builder code is defined in an npm package.
比如，BrowserBuilder 针对某个浏览器目标运行 webpack 构建，而 KarmaBuilder 则启动 Karma 服务器，并且针对单元测试运行 webpack 构建。
For example, BrowserBuilder runs a webpack build for a browser target and KarmaBuilder starts the Karma server and runs a webpack build for unit tests.
CLI 命令 ng run使用一个特定的目标配置来调用构建器。 工作空间配置文件 angular.json 中包含这些内置构建器的默认配置。
The CLI command ng runinvokes a builder with a specific target configuration. The workspace configuration file, angular.json, contains default configurations for built-in builders.
大小写类型（case types）
case types
Angular 使用大小写约定来区分多种名字，详见风格指南中的 "命名" 一节。下面是这些大小写类型的汇总表：
Angular uses capitalization conventions to distinguish the names of various types, as described in the naming guidelines section of the Style Guide. Here's a summary of the case types:
小驼峰形式（camelCase）：符号、属性、方法、管道名、非组件指令的选择器、常量。 小驼峰（也叫标准驼峰）形式的第一个字母要使用小写形式。比如 "selectedHero"。
camelCase : Symbols, properties, methods, pipe names, non-component directive selectors, constants. Standard or lower camel case uses lowercase on the first letter of the item. For example, "selectedHero".
大驼峰形式（UpperCamelCase）或叫帕斯卡形式（PascalCase）：类名（包括用来定义组件、接口、NgModule、指令、管道等的类）。 大驼峰形式的第一个字母要使用大写形式。比如 "HeroListComponent"。
UpperCamelCase (or PascalCase): Class names, including classes that define components, interfaces, NgModules, directives, and pipes, Upper camel case uses uppercase on the first letter of the item. For example, "HeroListComponent".
中线形式（dash-case）或叫烤串形式（kebab-case）：文件名中的描述部分，组件的选择器。比如 "app-hero-list"。
dash-case (or "kebab-case"): Descriptive part of file names, component selectors. For example, "app-hero-list".
下划线形式（underscore_case）或叫蛇形形式（snake_case）：在 Angular 中没有典型用法。蛇形形式使用下划线连接各个单词。 比如 "convert_link_mode"。
underscore_case (or "snake_case"): Not typically used in Angular. Snake case uses words connected with underscores. For example, "convert_link_mode".
大写下划线形式（UPPER_UNDERSCORE_CASE）或叫大写蛇形形式（UPPER_SNAKE_CASE）：传统的常量写法（可以接受，但更推荐用小驼峰形式（camelCase）） 大蛇形形式使用下划线分隔的全大写单词。比如 "FIX_ME" 。
UPPER_UNDERSCORE_CASE (or UPPER_SNAKE_CASE, or SCREAMING_SNAKE_CASE): Traditional for constants (acceptable, but prefer camelCase). Upper snake case uses words in all capital letters connected with underscores. For example, "FIX_ME".
变更检测（change detection）
change detection
Angular 框架会通过此机制将应用程序 UI 的状态与数据的状态同步。变更检测器在运行时会检查数据模型的当前状态，并在下一轮迭代时将其和先前保存的状态进行比较。
The mechanism by which the Angular framework synchronizes the state of an application's UI with the state of the data. The change detector checks the current state of the data model whenever it runs, and maintains it as the previous state to compare on the next iteration.
当应用逻辑更改组件数据时，绑定到视图中 DOM 属性上的值也要随之更改。变更检测器负责更新视图以反映当前的数据模型。类似地，用户也可以与 UI 进行交互，从而引发要更改数据模型状态的事件。这些事件可以触发变更检测。
As the application logic updates component data, values that are bound to DOM properties in the view can change. The change detector is responsible for updating the view to reflect the current data model. Similarly, the user can interact with the UI, causing events that change the state of the data model. These events can trigger change detection.
使用默认的（“CheckAlways”）变更检测策略，变更检测器将遍历每个视图模型上的视图层次结构 ，以检查模板中的每个数据绑定属性。在第一阶段，它将所依赖的数据的当前状态与先前状态进行比较，并收集更改。在第二阶段，它将更新页面上的 DOM 以反映出所有新的数据值。
Using the default ("CheckAlways") change-detection strategy, the change detector goes through the view hierarchy on each VM turn to check every data-bound property in the template. In the first phase, it compares the current state of the dependent data with the previous state, and collects changes. In the second phase, it updates the page DOM to reflect any new data values.
如果设置了 OnPush（“CheckOnce”）变更检测策略，则变更检测器仅在显式调用它或由 @Input 引用的变化或触发事件处理程序时运行。这通常可以提高性能。欲知详情，参见优化 Angular 的变更检测 。
If you set the OnPush ("CheckOnce") change-detection strategy, the change detector runs only when explicitly invoked, or when it is triggered by an Input reference change or event handler. This typically improves performance. For more information, see Optimize Angular's change detection.
类装饰器（class decorator）
class decorator
装饰器会出现在类定义的紧前方，用来声明该类具有指定的类型，并且提供适合该类型的元数据。
A decorator that appears immediately before a class definition, which declares the class to be of the given type, and provides metadata suitable to the type.
可以用下列装饰器来声明 Angular 的类：
The following decorators can declare Angular class types:
@Component()@Directive()@Pipe()@Injectable()@NgModule()
类字段装饰器（class field decorator）
class field decorator
出现在类定义中属性紧前方的装饰器语句用来声明该字段的类型。比如 @Input 和 @Output。
A decorator statement immediately before a field in a class definition that declares the type of that field. Some examples are @Input and @Output.
集合（collection）
collection
在 Angular 中，是指收录在同一个 npm 包 中的一组原理图（schematics）。
In Angular, a set of related schematics collected in an npm package.
命令行界面（CLI）
command-line interface (CLI)
Angular CLI 是一个命令行工具，用于管理 Angular 的开发周期。它用于为工作区或项目创建初始的脚手架，并且运行生成器（schematics）来为初始生成的版本添加或修改各类代码。 CLI 支持开发周期中的所有阶段，比如构建、测试、打包和部署。
The Angular CLI is a command-line tool for managing the Angular development cycle. Use it to create the initial filesystem scaffolding for a workspace or project, and to run schematics that add and modify code for initial generic versions of various elements. The CLI supports all stages of the development cycle, including building, testing, bundling, and deployment.
要开始使用 CLI 来创建新项目，参见建立本地开发环境。
To begin using the CLI for a new project, see Local Environment Setup.
要了解 CLI 的全部功能，参见 CLI 命令参考手册。
To learn more about the full capabilities of the CLI, see the CLI command reference.
参见 Schematics CLI。
See also Schematics CLI.
组件 (component)
component
一个带有 @Component() 装饰器的类，和它的伴生模板关联在一起。组件及其模板共同定义了一个视图。
A class with the @Component() decorator that associates it with a companion template. Together, the component and template define a view.
组件是指令的一种特例。@Component() 装饰器扩展了 @Directive() 装饰器，增加了一些与模板有关的特性。
A component is a special type of directive. The @Component() decorator extends the @Directive() decorator with template-oriented features.
Angular 的组件类负责暴露数据，并通过数据绑定机制来处理绝大多数视图的显示和用户交互逻辑。
An Angular component class is responsible for exposing data and handling most of the view's display and user-interaction logic through data binding.
要了解更多关于组件、模板和视图的知识，参见 架构概览 一章。
Read more about components, templates, and views in Architecture Overview.
配置（configuration）
configuration
参见工作空间配置
自定义元素（Custom element）
custom element
一种 Web 平台的特性，目前已经被绝大多数浏览器支持，在其它浏览器中也可以通过腻子脚本获得支持（参见浏览器支持）。
A web platform feature, currently supported by most browsers and available in other browsers through polyfills (see Browser support).
这种自定义元素特性通过允许你定义标签（其内容是由 JavaScript 代码来创建和控制的）来扩展 HTML。当自定义元素（也叫 Web Component）被添加到 CustomElementRegistry 之后就会被浏览器识别。
The custom element feature extends HTML by allowing you to define a tag whose content is created and controlled by JavaScript code. A custom element (also called a web component) is recognized by a browser when it's added to the CustomElementRegistry.
你可以使用 API 来转换 Angular 组件，以便它能够注册进浏览器中，并且可以用在你往 DOM 中添加的任意 HTML 中。 自定义元素标签可以把组件的视图（包括变更检测和数据绑定功能）插入到不受 Angular 控制的内容中。
You can use the API to transform an Angular component so that it can be registered with the browser and used in any HTML that you add directly to the DOM within an Angular app. The custom element tag inserts the component's view, with change-detection and data-binding functionality, into content that would otherwise be displayed without Angular processing.
参见 Angular 元素。
See Angular element.
参见加载动态组件。
See also dynamic component loading.
数据绑定 (data binding)
data binding
这个过程可以让应用程序将数据展示给用户，并对用户的操作（点击、触屏、按键）做出回应。
A process that allows apps to display data values to a user and respond to user actions (such as clicks, touches, and keystrokes).
在数据绑定机制下，你只要声明一下 HTML 部件和数据源之间的关系，把细节交给框架去处理。 而以前的手动操作过程是：将数据推送到 HTML 页面中、添加事件监听器、从屏幕获取变化后的数据，并更新应用中的值。
In data binding, you declare the relationship between an HTML widget and a data source and let the framework handle the details. Data binding is an alternative to manually pushing application data values into HTML, attaching event listeners, pulling changed values from the screen, and updating application data values.
更多的绑定形式，见模板语法：
Read about the following forms of binding in Template Syntax:
可声明对象（declarable）
declarable
类的一种类型，你可以把它们添加到 NgModule 的 declarations 列表中。 你可以声明组件、指令和管道。
A class type that you can add to the declarations list of an NgModule. You can declare components, directives, and pipes.
不要声明：
Don't declare the following:
已经在其它 NgModule 中声明过的类
A class that's already declared in another NgModule
从其它包中导入的指令数组。比如，不要再次声明来自
@angular/forms中的FORMS_DIRECTIVESAn array of directives imported from another package. For example, don't declare
FORMS_DIRECTIVESfrom@angular/formsNgModule 类
NgModule classes
服务类
Service classes
非 Angular 的类和对象，比如：字符串、数字、函数、实体模型、配置、业务逻辑和辅助类
Non-Angular classes and objects, such as strings, numbers, functions, entity models, configurations, business logic, and helper classes
装饰器（decorator | decoration）
decorator | decoration
一个函数，用来修饰紧随其后的类或属性定义。 装饰器（也叫注解）是 JavaScript 的一种语言特性，是一项位于阶段2（stage 2）的试验特性。
A function that modifies a class or property definition. Decorators (also called annotations) are an experimental (stage 2) JavaScript language feature. TypeScript adds support for decorators.
Angular 定义了一些装饰器，用来为类或属性附加元数据，来让自己知道那些类或属性的含义，以及该如何处理它们。
Angular defines decorators that attach metadata to classes or properties so that it knows what those classes or properties mean and how they should work.
See class decorator, class field decorator.
依赖注入（dependency injection）
dependency injection (DI)
依赖注入既是设计模式，同时又是一种机制：当应用程序的一些部件（即一些依赖）需要另一些部件时， 利用依赖注入来创建被请求的部件，并将它们注入到需要它们的部件中。
A design pattern and mechanism for creating and delivering some parts of an application (dependencies) to other parts of an application that require them.
在 Angular 中，依赖通常是服务，但是也可以是值，比如字符串或函数。应用的注入器（它是在启动期间自动创建的）会使用该服务或值的配置好的提供者来按需实例化这些依赖。各个不同的提供者可以为同一个服务提供不同的实现。
In Angular, dependencies are typically services, but they also can be values, such as strings or functions. An injector for an app (created automatically during bootstrap) instantiates dependencies when needed, using a configured provider of the service or value.
要了解更多，参见Angular 中的依赖注入一章。
Learn more in Dependency Injection in Angular.
DI 令牌（Token）
DI token
一种用来查阅的令牌，它关联到一个依赖提供者，用于依赖注入系统中。
A lookup token associated with a dependency provider, for use with the dependency injection system.
差异化加载
differential loading
一种构建技术，它会为同一个应用创建两个发布包。一个是较小的发布包，是针对现代浏览器的。另一个是较大的发布包，能让该应用正确的运行在像 IE 11 这样的老式浏览器上，这些浏览器不能支持全部现代浏览器的 API。
A build technique that creates two bundles for an application. One smaller bundle is for modern browsers. A second, larger bundle allows the application to run correctly in older browsers (such as IE11) that do not support all modern browser APIs.
欲知详情，参见 Deployment 一章。
For more information, see the Deployment guide.
指令 (directive)
directive
一个可以修改 DOM 结构或修改 DOM 和组件数据模型中某些属性的类。 指令类的定义紧跟在 @Directive() 装饰器之后，以提供元数据。
A class that can modify the structure of the DOM or modify attributes in the DOM and component data model. A directive class definition is immediately preceded by a @Directive() decorator that supplies metadata.
指令类几乎总与 HTML 元素或属性 (attribute) 相关。 通常会把这些 HTML 元素或者属性 (attribute) 当做指令本身。 当 Angular 在 HTML 模板中发现某个指令时，会创建与之相匹配的指令类的实例，并且把这部分 DOM 的控制权交给它。
A directive class is usually associated with an HTML element or attribute, and that element or attribute is often referred to as the directive itself. When Angular finds a directive in an HTML template, it creates the matching directive class instance and gives the instance control over that portion of the browser DOM.
指令分为三类：
There are three categories of directive:
组件使用
@Component()（继承自@Directive()）为某个类关联一个模板。Components use
@Component()(an extension of@Directive()) to associate a template with a class.属性型指令修改页面元素的行为和外观。
Attribute directives modify behavior and appearance of page elements.
结构型指令修改 DOM 的结构。
Structural directives modify the structure of the DOM.
Angular 提供了一些以 ng 为前缀的内置指令。你也可以创建新的指令来实现自己的功能。 你可以为自定义指令关联一个选择器（一种形如 <my-directive> 的 HTML 标记），以扩展模板语法，从而让你能在应用中使用它。
Angular supplies a number of built-in directives that begin with the ng prefix. You can also create new directives to implement your own functionality. You associate a selector (an HTML tag such as <my-directive>) with a custom directive, thereby extending the template syntax that you can use in your apps.
领域特定语言（DSL)
domain-specific language (DSL)
一种特殊用途的库或 API，参见领域特定语言词条。
A special-purpose library or API; see Domain-specific language.
Angular 使用领域特定语言扩展了 TypeScript，用于与 Angular 应用相关的许多领域。这些 DSL 都定义在 NgModule 中，比如 动画、表单和路由与导航。
Angular extends TypeScript with domain-specific languages for a number of domains relevant to Angular apps, defined in NgModules such as animations, forms, and routing and navigation.
动态组件加载（dynamic component loading）
dynamic component loading
一种在运行期间把组件添加到 DOM 中的技术，它需要你从编译期间排除该组件，然后，当你把它添加到 DOM 中时，再把它接入 Angular 的变更检测与事件处理框架。
A technique for adding a component to the DOM at run time. Requires that you exclude the component from compilation and then connect it to Angular's change-detection and event-handling framework when you add it to the DOM.
参见自定义元素，它提供了一种更简单的方式来达到相同的效果。
See also custom element, which provides an easier path with the same result.
急性加载（Eager Loading）
eager loading
在启动时加载的 NgModule 和组件被称为急性加载，与之相对的是那些在运行期间才加载的方式（惰性加载）。 参见惰性加载。
NgModules or components that are loaded on launch are called eager-loaded, to distinguish them from those that are loaded at run time (lazy-loaded). See lazy loading.
ECMAScript 语言
ECMAScript
The official JavaScript language specification.
并不是所有浏览器都支持最新的 ECMAScript 标准，不过你可以使用转译器（比如TypeScript）来用最新特性写代码，然后它会被转译成可以在浏览器的其它版本上运行的代码。
Not all browsers support the latest ECMAScript standard, but you can use a transpiler (like TypeScript) to write code using the latest features, which will then be transpiled to code that runs on versions that are supported by browsers.
要了解更多，参见浏览器支持页。
To learn more, see Browser Support.
元素（Element）
element
Angular 定义了 ElementRef 类来包装与渲染有关的原生 UI 元素。这让你可以在大多数情况下使用 Angular 的模板和数据绑定机制来访问 DOM 元素，而不必再引用原生元素。
Angular defines an ElementRef class to wrap render-specific native UI elements. In most cases, this allows you to use Angular templates and data binding to access DOM elements without reference to the native element.
本文档中一般会使用元素（Element）来指代 ElementRef 的实例，注意与 DOM 元素（你必要时你可以直接访问它）区分开。
The documentation generally refers to elements (ElementRef instances), as distinct from DOM elements (which can be accessed directly if necessary).
可以对比下自定义元素。
Compare to custom element.
入口点（Entry Point）
entry point
JavaScript 模块(#module)的目的是供 npm 包的用户进行导入。入口点模块通常会重新导出来自其它内部模块的一些符号。每个包可以包含多个入口点。比如 @angular/core 就有两个入口点模块，它们可以使用名字 @angular/core 和 @angular/core/testing 进行导入。
A JavaScript module(#module) that is intended to be imported by a user of an npm package. An entry-point module typically re-exports symbols from other internal modules. A package can contain multiple entry points. For example, the @angular/core package has two entry-point modules, which can be imported using the module names @angular/core and @angular/core/testing.
表单控件（form control）
form control
一个 FormControl 实例，它是 Angular 表单的基本构造块。它会和 FormGroup 和 FormArray 一起，跟踪表单输入元素的值、有效性和状态。
A instance of FormControl, which is a fundamental building block for Angular forms. Together with FormGroup and FormArray, tracks the value, validation, and status of a form input element.
欲知详情，参见 Angular 表单简介。
Read more forms in the Introduction to forms in Angular.
表单模型（form model）
form model
是指在指定的时间点，表单输入元素的值和验证状态的"权威数据源"。当使用响应式表单时，表单模型会在组件类中显式创建。当使用模板驱动表单时，表单模型是由一些指令隐式创建的。
The "source of truth" for the value and validation status of a form input element at a given point in time. When using reactive forms, the form model is created explicitly in the component class. When using template-driven forms, the form model is implicitly created by directives.
要深入了解响应式表单和模板驱动表单，参见 Angular 表单简介。
Learn more about reactive and template-driven forms in the Introduction to forms in Angular.
表单验证（form validation）
form validation
一种检查，当表单值发生变化时运行，并根据预定义的约束来汇报指定的这些值是否正确并完全。响应式表单使用验证器函数，而模板驱动表单则使用验证器指令。
A check that runs when form values change and reports whether the given values are correct and complete, according to the defined constraints. Reactive forms apply validator functions. Template-driven forms use validator directives.
要了解更多，参见表单验证器。
To learn more, see Form Validation.
不可变性（immutability）
immutability
是否能够在创建之后修改值的状态。响应式表单会执行不可变性的更改，每次更改数据模型都会生成一个新的数据模型，而不是修改现有的数据模型。 模板驱动表单则会执行可变的更改，它通过 NgModel 和双向数据绑定来就地修改现有的数据模型。
The ability to alter the state of a value after its creation. Reactive forms perform immutable changes in that each change to the data model produces a new data model rather than modifying the existing one. Template-driven forms perform mutable changes with NgModel and two-way data binding to modify the existing data model in place.
可注入对象（injectable）
injectable
Angular 中的类或其它概念使用依赖注入机制来提供依赖。 可供注入的服务类必须使用@Injectable() 装饰器标出来。其它条目，比如常量值，也可用于注入。
An Angular class or other definition that provides a dependency using the dependency injection mechanism. An injectable service class must be marked by the @Injectable() decorator. Other items, such as constant values, can also be injectable.
注入器 (injector)
injector
Angular 依赖注入系统中可以在缓存中根据名字查找依赖，也可以通过配置过的提供者来创建依赖。 启动过程中会自动为每个模块创建一个注入器，并被组件树继承。
An object in the Angular dependency-injection system that can find a named dependency in its cache or create a dependency using a configured provider. Injectors are created for NgModules automatically as part of the bootstrap process and are inherited through the component hierarchy.
注入器会提供依赖的一个单例，并把这个单例对象注入到多个组件中。
An injector provides a singleton instance of a dependency, and can inject this same instance in multiple components.
模块和组件级别的注入器树可以为它们拥有的组件及其子组件提供同一个依赖的不同实例。
A hierarchy of injectors at the NgModule and component level can provide different instances of a dependency to their own components and child components.
你可以为同一个依赖使用不同的提供者来配置这些注入器，这些提供者可以为同一个依赖提供不同的实现。
You can configure injectors with different providers that can provide different implementations of the same dependency.
要了解关于多级注入器的更多知识，参见多级依赖注入一章。
Learn more about the injector hierarchy in Hierarchical Dependency Injectors.
输入属性 (input)
input
当定义指令时，指令属性上的 @Input() 装饰器让该属性可以作为属性绑定的目标使用。 数据值会从等号右侧的模板表达式所指定的数据源流入组件的输入属性。
When defining a directive, the @Input() decorator on a directive property makes that property available as a target of a property binding. Data values flow into an input property from the data source identified in the template expression to the right of the equal sign.
要了解更多，参见输入与输出属性。
To learn more, see input and output properties.
插值 (interpolation)
interpolation
属性数据绑定 (property data binding) 的一种形式，位于双大括号中的模板表达式 (template expression)会被渲染成文本。 在被赋值给元素属性或者显示在元素标签中之前，这些文本可能会先与周边的文本合并，参见下面的例子。
A form of property data binding in which a template expression between double-curly braces renders as text. That text can be concatenated with neighboring text before it is assigned to an element property or displayed between element tags, as in this example.
Read more about interpolation in Template Syntax.
常春藤引擎（Ivy）
Ivy
Ivy 是 Angular 的下一代编译和渲染管道的代号。在 Angular 的版本 9 中，默认情况下使用新的编译器和运行时，而不再用旧的编译器和运行时，也就是 View Engine 。
Ivy is the code name for Angular's next-generation compilation and rendering pipeline. With the version 9 release of Angular, the new compiler and runtime instructions are used by default instead of the older compiler and runtime, known as View Engine.
参见 Angular Ivy。
See Angular Ivy.
JavaScript
参见 ECMAScript 和 TypeScript。
See ECMAScript, TypeScript.
即时 (just-in-time, JIT) 编译
just-in-time (JIT) compilation
在启动期间，Angular 的即时编译器（JIT)会在运行期间把你的 Angular HTML 和 TypeScript 代码转换成高效的 JavaScript 代码。
The Angular just-in-time (JIT) compiler converts your Angular HTML and TypeScript code into efficient JavaScript code at run time, as part of bootstrapping.
当你运行 Angular 的 CLI 命令 ng build 和 ng serve 时，JIT 编译是默认选项，而且是开发期间的最佳实践。但是强烈建议你不要在生产环境下使用 JIT 模式，因为它会导致巨大的应用负担，从而拖累启动时的性能。
JIT compilation is the default (as opposed to AOT compilation) when you run Angular's ng build and ng serve CLI commands, and is a good choice during development. JIT mode is strongly discouraged for production use because it results in large application payloads that hinder the bootstrap performance.
参见预先 (AOT) 编译。
Compare to ahead-of-time (AOT) compilation.
惰性加载（Lazy loading）
lazy loading
惰性加载过程会把应用拆分成多个包并且按需加载它们，从而提高应用加载速度。 比如，一些依赖可以根据需要进行惰性加载，与之相对的是那些 急性加载 的模块，它们是根模块所要用的，因此会在启动期间加载。
A process that speeds up application load time by splitting the application into multiple bundles and loading them on demand. For example, dependencies can be lazy loaded as needed—as opposed to eager-loaded modules that are required by the root module and are thus loaded on launch.
路由器只有当父视图激活时才需要加载子视图。同样，你还可以构建一些自定义元素，它们也可以在需要时才加载进 Angular 应用。
The router makes use of lazy loading to load child views only when the parent view is activated. Similarly, you can build custom elements that can be loaded into an Angular app when needed.
库（Library）
library
一种 Angular 项目。用来让其它 Angular 应用包含它，以提供各种功能。库不是一个完整的 Angular 应用，不能独立运行。（要想为非 Angular 应用添加可复用的 Angular 功能，你可以使用 Angular 的自定义元素。）
In Angular, a project that provides functionality that can be included in other Angular apps. A library isn't a complete Angular app and can't run independently. (To add re-usable Angular functionality to non-Angular web apps, you can use Angular custom elements.)
库的开发者可以使用 CLI 在现有的 工作区 中
generate新库的脚手架，还能把库发布为npm包。Library developers can use the Angular CLI to
generatescaffolding for a new library in an existing workspace, and can publish a library as annpmpackage.应用开发者可以使用 CLI 来把一个已发布的库
add进这个应用所在的工作区。Application developers can use the Angular CLI to
adda published library for use with an application in the same workspace.
参见 原理图（schematic）。
See also schematic.
生命周期钩子（Lifecycle hook）
lifecycle hook
一种接口，它允许你监听指令和组件的生命周期，比如创建、更新和销毁等。
An interface that allows you to tap into the lifecycle of directives and components as they are created, updated, and destroyed.
每个接口只有一个钩子方法，方法名是接口名加前缀 ng。例如，OnInit 接口的钩子方法名为 ngOnInit。
Each interface has a single hook method whose name is the interface name prefixed with ng. For example, the OnInit interface has a hook method named ngOnInit.
Angular 会按以下顺序调用钩子方法：
Angular calls these hook methods in the following order:
ngOnChanges- 在输入属性 (input)/输出属性 (output)的绑定值发生变化时调用。ngOnInit- 在第一次ngOnChanges完成后调用。ngOnInit: After the firstngOnChanges.ngDoCheck- 开发者自定义变更检测。ngDoCheck: Developer's custom change detection.ngAfterContentInit- 在组件内容初始化后调用。ngAfterContentInit: After component content initialized.ngAfterContentChecked- 在组件内容每次检查后调用。ngAfterContentChecked: After every check of component content.ngAfterViewInit- 在组件视图初始化后调用。ngAfterViewInit: After a component's views are initialized.ngAfterViewChecked- 在组件视图每次检查后调用。ngAfterViewChecked: After every check of a component's views.ngOnDestroy- 在指令销毁前调用。ngOnDestroy: Just before the directive is destroyed.
要了解更多，参见生命周期钩子页。
To learn more, see Lifecycle Hooks.
模块 (module)
module
通常，模块会收集一组专注于单一目的的代码块。Angular 既使用 JavaScript 的标准模块，也定义了 Angular 自己的模块，也就是 NgModule。
In general, a module collects a block of code dedicated to a single purpose. Angular uses standard JavaScript modules and also defines an Angular module, NgModule.
在 JavaScript (ECMAScript) 中，每个文件都是一个模块，该文件中定义的所有对象都属于这个模块。这些对象可以导出为公共对象，而这些公共对象可以被其它模块导入后使用。
In JavaScript (ECMAScript), each file is a module and all objects defined in the file belong to that module. Objects can exported, making them public, and public objects can be imported for use by other modules.
Angular 就是用一组 JavaScript 模块（也叫库）的形式发布的。每个 Angular 库都带有 @angular 前缀。 使用 NPM 包管理器安装它们，并且使用 JavaScript 的 import 声明语句从中导入各个部件。
Angular ships as a collection of JavaScript modules (also called libraries). Each Angular library name begins with the @angular prefix. Install Angular libraries with the npm package manager and import parts of them with JavaScript import declarations.
参见 NgModule。
Compare to NgModule.
ngcc
Angular 兼容性编译器。如果使用 Ivy 构建应用程序，但依赖未用 Ivy 编译的库，则 CLI 将使用 ngcc 自动更新依赖库以使用 Ivy。
Angular compatability compiler. If you build your app using Ivy, but it depends on libraries have not been compiled with Ivy, the CLI uses ngcc to automatically update the dependent libraries to use Ivy.
NgModule
一种带有 @NgModule() 装饰器的类定义，它会声明并提供一组专注于特定功能的代码块，比如业务领域、工作流或一组紧密相关的能力集等。
A class definition preceded by the @NgModule() decorator, which declares and serves as a manifest for a block of code dedicated to an application domain, a workflow, or a closely related set of capabilities.
像 JavaScript 模块一样，NgModule 能导出那些可供其它 NgModule 使用的功能，也可以从其它 NgModule 中导入其公开的功能。 NgModule 类的元数据中包括一些供应用使用的组件、指令和管道，以及导入、导出列表。参见可声明对象。
Like a JavaScript module, an NgModule can export functionality for use by other NgModules and import public functionality from other NgModules. The metadata for an NgModule class collects components, directives, and pipes that the application uses along with the list of imports and exports. See also declarable.
NgModule 通常会根据它导出的内容决定其文件名，比如，Angular 的 DatePipe 类就属于 date_pipe.ts 文件中一个名叫 date_pipe 的特性模块。 你可以从 Angular 的范围化包中导入它们，比如 @angular/core 。
NgModules are typically named after the file in which the exported thing is defined. For example, the Angular DatePipe class belongs to a feature module named date_pipe in the file date_pipe.ts. You import them from an Angular scoped package such as @angular/core.
每个 Angular 应用都有一个根模块。通常，这个类会命名为 AppModule，并且位于一个名叫 app.module.ts 的文件中。
Every Angular application has a root module. By convention, the class is called AppModule and resides in a file named app.module.ts.
要了解更多，参见 NgModules。
To learn more, see NgModules.
npm 包
npm package
npm 包管理器用于分发与加载 Angular 的模块和库。
The npm package manager is used to distribute and load Angular modules and libraries.
你还可以了解 Angular 如何使用 Npm 包 的更多知识。
Learn more about how Angular uses Npm Packages.
可观察对象（Observable）
observable
一个多值生成器，这些值会被推送给订阅者。 Angular 中到处都会用到异步事件处理。你要通过调用可观察对象的 subscribe() 方法来订阅它，从而让这个可观察对象得以执行，你还要给该方法传入一些回调函数来接收 "有新值"、"错误" 或 "完成" 等通知。
A producer of multiple values, which it pushes to subscribers. Used for asynchronous event handling throughout Angular. You execute an observable by subscribing to it with its subscribe() method, passing callbacks for notifications of new values, errors, or completion.
可观察对象可以把任意类型的一个或多个值传给订阅者，无论是同步（就像函数把值返回给它的调用者一样）还是异步。 订阅者会在生成了新值时收到包含这个新值的通知，以及正常结束或错误结束时的通知。
Observables can deliver single or multiple values of any type to subscribers, either synchronously (as a function delivers a value to its caller) or on a schedule. A subscriber receives notification of new values as they are produced and notification of either normal completion or error completion.
Angular 使用一个名叫响应式扩展 (RxJS)的第三方包来实现这些功能。
Angular uses a third-party library called Reactive Extensions (RxJS).
要了解更多，参见可观察对象。
To learn more, see Observables.
观察者（Observer）
observer
传给可观察对象 的 subscribe() 方法的一个对象，其中定义了订阅者的一组回调函数。
An object passed to the subscribe() method for an observable. The object defines the callbacks for the subscriber.
输出属性 (output)
output
当定义指令时，指令属性上的 @Output() 装饰器会让该属性可用作事件绑定的目标。 事件从该属性流出到等号右侧指定的模板表达式中。
When defining a directive, the @Output{} decorator on a directive property makes that property available as a target of event binding. Events stream out of this property to the receiver identified in the template expression to the right of the equal sign.
要了解更多，参见输入与输出属性。
To learn more, see Input and Output Properties.
管道（pipe）
pipe
一个带有 @Pipe{} 装饰器的类，它定义了一个函数，用来把输入值转换成输出值，以显示在视图中。 Angular 定义了很多管道，并且你还可可以自定义新的管道。
A class which is preceded by the @Pipe{} decorator and which defines a function that transforms input values to output values for display in a view. Angular defines various pipes, and you can define new pipes.
要了解更多，参见管道页。
To learn more, see Pipes.
平台（platform）
platform
在 Angular 术语中，平台是供 Angular 应用程序在其中运行的上下文。 Angular 应用程序最常见的平台是 Web 浏览器，但它也可以是移动设备的操作系统或 Web 服务器。
In Angular terminology, a platform is the context in which an Angular application runs. The most common platform for Angular applications is a web browser, but it can also be an operating system for a mobile device, or a web server.
@angular/platform-* 软件包提供了对各种 Angular 运行时平台的支持。这些软件包通过提供用于收集用户输入和渲染指定平台 UI 的实现，以允许使用 @angular/core 和 @angular/common 的应用程序在不同的环境中执行。隔离平台相关的功能使开发人员可以独立于平台使用框架的其余部分。
Support for the various Angular run-time platforms is provided by the @angular/platform-* packages. These packages allow applications that make use of @angular/core and @angular/common to execute in different environments by providing implementation for gathering user input and rendering UIs for the given platform. Isolating platform-specific functionality allows the developer to make platform-independent use of the rest of the framework.
在 Web 浏览器中运行时，
BrowserModule是从platform-browser软件包中导入的，并支持简化安全性和事件处理的服务，并允许应用程序访问浏览器专有的功能，例如解释键盘输入和控制文档要显示的标题。浏览器中运行的所有应用程序都使用同一个平台服务。When running in a web browser,
BrowserModuleis imported from theplatform-browserpackage, and supports services that simplify security and event processing, and allows applications to access browser-specific features, such as interpreting keyboard input and controlling the title of the document being displayed. All applications running in the browser use the same platform service.
使用服务端渲染（SSR）时，
platform-server包将提供DOM、XMLHttpRequest和其他不依赖浏览器的其他底层功能的 Web 服务器端实现。When server-side rendering (SSR) is used, the
platform-serverpackage provides web server implementations of theDOM,XMLHttpRequest, and other low-level features that don't rely on a browser.
腻子脚本（polyfill）
polyfill
一个 NPM 包，它负责弥补浏览器 JavaScript 实现与最新标准之间的 "缝隙"。参见浏览器支持页，以了解要在特定平台支持特定功能时所需的腻子脚本。
An npm package that plugs gaps in a browser's JavaScript implementation. See Browser Support for polyfills that support particular functionality for particular platforms.
项目（project）
project
在 Angular CLI 中，CLI 命令可能会创建或修改独立应用或库。
In the Angular CLI, a standalone application or library that can be created or modified by a CLI command.
由 ng new创建的项目中包含一组源文件、资源和配置文件，当你用 CLI 开发或测试此应用时就会用到它们。此外，还可以用 ng generate application 或 ng generate library 命令创建项目。
A project, as generated by the ng new, contains the set of source files, resources, and configuration files that you need to develop and test the application using the CLI. Projects can also be created with the ng generate application and ng generate library commands.
欲知详情，参见项目文件结构。
For more information, see Project File Structure.
angular.json文件可以配置某个工作空间 中的所有项目。
The angular.jsonfile configures all projects in a workspace.
提供者 (provider)
provider
一个实现了 Provider接口的对象。一个提供者对象定义了如何获取与 DI 令牌（token） 相关联的可注入依赖。 注入器会使用这个提供者来创建它所依赖的那些类的实例。
An object that implements one of the Providerinterfaces. A provider object defines how to obtain an injectable dependency associated with a DI token. An injector uses the provider to create a new instance of a dependency for a class that requires it.
Angular 会为每个注入器注册一些 Angular 自己的服务。你也可以注册应用自己所需的服务提供者。
Angular registers its own providers with every injector, for services that Angular defines. You can register your own providers for services that your app needs.
See also service, dependency injection.
欲知详情，参见依赖注入。
Learn more in Dependency Injection.
响应式表单 (reactive forms)
reactive forms
通过组件中代码构建 Angular 表单的一个框架。 另一种技术是模板驱动表单
A framework for building Angular forms through code in a component. The alternative is a template-driven form.
构建响应式表单时：
When using reactive forms:
"权威数据源"（表单模型）定义在组件类中。
The "source of truth", the form model, is defined in the component class.
表单验证在组件代码而不是验证器指令中定义。
Validation is set up through validation functions rather than valdation directives.
在组件类中，使用
new FormControl()或者FormBuilder显性地创建每个控件。Each control is explicitly created in the component class by creating a
FormControlinstance manually or withFormBuilder.模板中的
input元素不使用ngModel。The template input elements do not use
ngModel.相关联的 Angular 指令全部以
Form开头，例如FormGroup()、FormControl()和FormControlName()。The associated Angular directives are prefixed with
form, such asformControl,formGroup, andformControlName.
另一种方式是模板驱动表单。模板驱动表单的简介和这两种方式的比较，参见 Angular 表单简介。
The alternative is a template-driven form. For an introduction and comparison of both forms approaches, see Introduction to Angular Forms.
路由器 (router)
router
一种工具，用来配置和实现 Angular 应用中各个状态和视图之间的导航。
A tool that configures and implements navigation among states and views within an Angular app.
Router 模块是一个 NgModule，它提供在应用视图间导航时需要的服务提供者和指令。路由组件是一种组件，它导入了 Router 模块，并且其模板中包含 RouterOutlet 元素，路由器生成的视图就会被显示在那里。
The Router module is an NgModule that provides the necessary service providers and directives for navigating through application views. A routing component is one that imports the Router module and whose template contains a RouterOutlet element where it can display views produced by the router.
路由器定义了在单页面中的各个视图之间导航的方式，而不是在页面之间。它会解释类似 URL 的链接，以决定该创建或销毁哪些视图，以及要加载或卸载哪些组件。它让你可以在 Angular 应用中获得惰性加载的好处。
The router defines navigation among views on a single page, as opposed to navigation among pages. It interprets URL-like links to determine which views to create or destroy, and which components to load or unload. It allows you to take advantage of lazy loading in your Angular apps.
要了解更多，参见路由与导航。
To learn more, see Routing and Navigation.
路由出口（router outlet）
router outlet
一种指令，它在路由组件的模板中扮演占位符的角色，Angular 会根据当前的路由状态动态填充它。
A directive that acts as a placeholder in a routing component's template. Angular dynamically renders the template based on the current router state.
路由组件 (routing component)
routing component
一个模板中带有 RouterOutlet 指令的 Angular 组件，用于根据路由器的导航显示相应的视图。
An Angular component with a RouterOutlet directive in its template that displays views based on router navigations.
要了解更多，参见路由与导航。
For more information, see Routing and Navigation.
规则（rule）
rule
在原理图 中，是指一个在文件树上运行的函数，用于以指定方式创建、删除或修改文件，并返回一个新的 Tree 对象。
In schematics, a function that operates on a file tree to create, delete, or modify files in a specific manner.
原理图（schematic）
schematic
脚手架库会定义如何借助创建、修改、重构或移动文件和代码等操作来生成或转换某个项目。每个原理图定义了一些规则，以操作一个被称为文件树的虚拟文件系统。
A scaffolding library that defines how to generate or transform a programming project by creating, modifying, refactoring, or moving files and code. A schematic defines rules that operate on a virtual file system called a tree.
Angular CLI 使用原理图来生成和修改 Angular 项目及其部件。
The Angular CLI uses schematics to generate and modify Angular projects and parts of projects.
Angular 提供了一组用于 CLI 的原理图。参见 Angular CLI 命令参考手册。当
ng add命令向项目中添加某个库时，就会运行原理图。ng generate命令则会运行原理图，来创建应用、库和 Angular 代码块。Angular provides a set of schematics for use with the CLI. See the Angular CLI command reference. The
ng addcommand runs schematics as part of adding a library to your project. Theng generatecommand runs schematics to create apps, libraries, and Angular code constructs.公共库的开发者可以创建原理图，来让 CLI 生成他们自己的发布的库。欲知详情，参见 devkit 文档。
Library developers can create schematics that enable the Angular CLI to add and update their published libraries, and to generate artifacts the library defines. Add these schematics to the npm package that you use to publish and share your library.
欲知详情，参见原理图和把库与 CLI 集成。
For more information, see Schematics and Integrating Libraries with the CLI.
Schematics CLI
Schematics 自带了一个命令行工具。 使用 Node 6.9 或更高版本，可以全局安装这个 Schematics CLI：
Schematics come with their own command-line tool. Using Node 6.9 or above, install the Schematics CLI globally:
npm install -g @angular-devkit/schematics-cli
这会安装可执行文件 schematics，你可以用它来创建新工程、往现有工程中添加新的 schematic，或扩展某个现有的 schematic。
This installs the schematics executable, which you can use to create a new schematics collection with an initial named schematic. The collection folder is a workspace for schematics. You can also use the schematics command to add a new schematic to an existing collection, or extend an existing schematic.
范围化包 (scoped package)
scoped package
一种把相关的 npm 包分组到一起的方式。 Angular 的 NgModule 都是在一些以 @angular 为范围名的范围化包中发布的。比如 @angular/core、@angular/common、@angular/forms 和 @angular/router。
A way to group related npm packages. NgModules are delivered within scoped packages whose names begin with the Angular scope name @angular. For example, @angular/core, @angular/common, @angular/forms, and @angular/router.
和导入普通包相同的方式导入范围化包。
Import a scoped package in the same way that you import a normal package.
import { Component } from '@angular/core';
服务端渲染
server-side rendering
一项在服务端生成静态应用页面的技术，它可以在对来自浏览器的请求进行响应时生成这些页面或用它们提供服务。 它还可以提前把这些页面生成为 HTML 文件，以便稍后用它们来提供服务。
A technique that generates static application pages on the server, and can generate and serve those pages in response to requests from browsers. It can also pre-generate pages as HTML files that you serve later.
该技术可以增强手机和低功耗设备的性能，而且会在应用加载通过快速展示一个静态首屏来提升用户体验。这个静态版本还能让你的应用对网络蜘蛛更加友好。
This technique can improve performance on mobile and low-powered devices and improve the user experience by showing a static first page quickly while the client-side app is loading. The static version can also make your app more visible to web crawlers.
你可以通过 CLI 运行 Angular Universal 工具，借助 @nguniversal/express-engine schematic 原理图来更轻松的让应用支持服务端渲染。
You can easily prepare an app for server-side rendering by using the CLI to run the Angular Universal tool, using the @nguniversal/express-engine schematic.
服务 (service)
service
在 Angular 中，服务就是一个带有 @Injectable 装饰器的类，它封装了可以在应用程序中复用的非 UI 逻辑和代码。 Angular 把组件和服务分开，是为了增进模块化程度和可复用性。
In Angular, a class with the @Injectable() decorator that encapsulates non-UI logic and code that can be reused across an application. Angular distinguishes components from services to increase modularity and reusability.
@Injectable 元数据让服务类能用于依赖注入机制中。可注入的类是用提供者进行实例化的。 各个注入器会维护一个提供者的列表，并根据组件或其它服务的需要，用它们来提供服务的实例。
The @Injectable() metadata allows the service class to be used with the dependency injection mechanism. The injectable class is instantiated by a provider. Injectors maintain lists of providers and use them to provide service instances when they are required by components or other services.
要了解更多，参见服务与依赖注入简介。
To learn more, see Introduction to Services and Dependency Injection.
结构型指令（Structural directives）
structural directives
一种指令类型，它能通过修改 DOM （添加、删除或操纵元素及其子元素）来修整或重塑 HTML 的布局。
A category of directive that is responsible for shaping HTML layout by modifying the DOM&mdashthat is, adding, removing, or manipulating elements and their children.
要了解更多，参见结构型指令页。
To learn more, see Structural Directives.
订阅者（Subscriber）
subscriber
一个函数，用于定义如何获取或生成要发布的值或消息。 当有消费者调用可观察对象的 subscribe() 方法时，该函数就会执行。
A function that defines how to obtain or generate values or messages to be published. This function is executed when a consumer calls the subscribe() method of an observable.
订阅一个可观察对象就会触发该对象的执行、为该对象关联一些回调函数，并创建一个 Subscription（订阅记录）对象来让你能取消订阅。
The act of subscribing to an observable triggers its execution, associates callbacks with it, and creates a Subscription object that lets you unsubscribe.
subscribe() 方法接收一个 JavaScript 对象（叫做观察者（observer）），其中最多可以包含三个回调，分别对应可观察对象可以发出的几种通知类型：
The subscribe() method takes a JavaScript object (called an observer) with up to three callbacks, one for each type of notification that an observable can deliver:
next（下一个）通知会发送一个值，比如数字、字符串、对象。The
nextnotification sends a value such as a number, a string, or an object.error（错误）通知会发送 JavaScript 错误或异常。The
errornotification sends a JavaScript Error or exception.complete（完成）通知不会发送值，但是当调用结束时会调用这个处理器。异步的值可能会在调用了完成之后继续发送过来。The
completenotification doesn't send a value, but the handler is called when the call completes. Scheduled values can continue to be returned after the call completes.
目标
target
项目的一个可构建或可运行的子集，它是工作空间配置文件中的一个子对象，它会被建筑师（Architect）的构建器（Builder）执行。
A buildable or runnable subset of a project, configured as an object in the workspace configuration file, and executed by an Architect builder.
在 angular.json 文件中，每个项目都有一个 architect 分区，其中包含一些用于配置构建器的目标。其中一些目标对应于 CLI 命令，比如 build、serve、test 和 lint。
In the angular.json file, each project has an "architect" section that contains targets which configure builders. Some of these targets correspond to CLI commands, such as build, serve, test, and lint.
比如，ng build 命令用来编译项目时所调用的构建器会使用一个特定的构建工具，并且具有一份默认配置，此配置中的值可以通过命令行参数进行覆盖。目标 build 还为 "生产环境" 构建定义了另一个配置，可以通过在 build 命令上添加 --prod 标志来调用它。
For example, the Architect builder invoked by the ng build command to compile a project uses a particular build tool, and has a default configuration whose values can be overridden on the command line. The build target also defines an alternate configuration for a "production" build, that can be invoked with the --prod flag on the build command.
建筑师工具提供了一组构建器。ng new 命令为初始应用项目提供了一组目标。ng generate application和 ng generate library命令则为每个新项目提供了一组目标。这些目标的选项和配置都可以进行自定义，以便适应你项目的需求。比如，你可能会想为项目的 "build" 目标添加一个 "staging" 或 "testing" 配置。
The Architect tool provides a set of builders. The ng new command provides a set of targets for the initial application project. The ng generate applicationand ng generate librarycommands provide a set of targets for each new project. These targets, their options and configurations, can be customized to meet the needs of your project. For example, you may want to add a "staging" or "testing" configuration to a project's "build" target.
你还可以定义一个自定义构建器，并且往项目配置中添加一个目标，来使用你的自定义构建器。然后你就可以通过 ng run命令来运行此目标。
You can also define a custom builder, and add a target to the project configuration that uses your custom builder. You can then run the target using the ng runCLI command.
模板 (template)
template
模板是与组件相关的代码，用来定义如何在 HTML 中渲染组件的视图。
Code associated with a component that defines how to render the component's view.
模板会把纯 HTML 和 Angular 的数据绑定语法、指令和模板表达式组合起来。Angular 的元素会插入或计算那些值，以便在页面显示出来之前修改 HTML 元素。
A template combines straight HTML with Angular data-binding syntax, directives, and template expressions (logical constructs). The Angular elements insert or calculate values that modify the HTML elements before the page is displayed.
模板通过 @Component() 装饰器与组件类关联起来。其 HTML 可以作为 template 属性的值用内联的方式提供，也可以通过 templateUrl 属性链接到一个独立的 HTML 文件。
A template is associated with a component class through the @Component() decorator. The HTML can be provided inline, as the value of the template property, or in a separate HTML file linked through the templateUrl property.
用 TemplateRef 对象表示的其它模板用来定义一些备用视图或内嵌视图，它们可以来自多个不同的组件。
Additional templates, represented by TemplateRef objects, can define alternative or embedded views, which can be referenced from multiple components.
模板驱动表单（template-driven forms）
template-driven forms
一种在视图中使用 HTML 表单和输入类元素构建 Angular 表单的格式。 它的替代方案是响应式表单框架。
A format for building Angular forms using HTML forms and input elements in the view. The alternative format uses the reactive forms framework.
当构建模板驱动表单时：
When using template-driven forms:
模板是“权威数据源”。使用属性 (attribute) 在单个输入元素上定义验证规则。
The "source of truth" is the template. The validation is defined using attributes on the individual input elements.
使用
ngModel进行双向绑定，保持组件模型和用户输入之间的同步。Two-way binding with
ngModelkeeps the component model synchronized with the user's entry into the input elements.在幕后，Angular 为每个带有
name属性和双向绑定的输入元素创建了一个新的控件。Behind the scenes, Angular creates a new control for each input element, provided you have set up a
nameattribute and two-way binding for each input.相关的 Angular 指令都带有
ng前缀，例如ngForm、ngModel和ngModelGroup。The associated Angular directives are prefixed with
ngsuch asngForm,ngModel, andngModelGroup.
另一种方式是响应式表单。响应式表单的简介和两种方式的比较参见 Angular 表单简介。
The alternative is a reactive form. For an introduction and comparison of both forms approaches, see Introduction to Angular Forms.
模板表达式（template expression）
template expression
一种类似 TypeScript 的语法，Angular 用它对数据绑定 (data binding)进行求值。
A TypeScript-like syntax that Angular evaluates within a data binding.
到模板表达式部分了解更多模板表达式的知识。
Read about how to write template expressions in Template expressions.
令牌（Token）
token
用于高效查表的不透明标识符（译注：不透明是指你不必了解其细节）。在 Angular 中，DI 令牌用于在依赖注入系统中查找服务提供者。
An opaque identifier used for efficient table lookup. In Angular, a DI token is used to find providers of dependencies in the dependency injection system.
转译（transpile)
transpile
一种翻译过程，它会把一个版本的 JavaScript 转换成另一个版本，比如把下一版的 ES2015 转换成老版本的 ES5。
The translation process that transforms one version of JavaScript to another version; for example, down-leveling ES2015 to the older ES5 version.
目录树（tree）
tree
在 schematics 中，一个用 Tree 类表示的虚拟文件系统。 Schematic 规则以一个 tree 对象作为输入，对它们进行操作，并且返回一个新的 tree 对象。
In schematics, a virtual file system represented by the Tree class. Schematic rules take a tree object as input, operate on them, and return a new tree object.
TypeScript
TypeScript 是一种基于 JavaScript 的程序设计语言，以其可选类型系统著称。 TypeScript 提供了编译时类型检查和强大的工具支持（比如代码补齐、重构、内联文档和智能搜索等）。 许多代码编辑器和 IDE 都原生支持 TypeScript 或通过插件提供支持。
A programming language based on JavaScript that is notable for its optional typing system. TypeScript provides compile-time type checking and strong tooling support (such as code completion, refactoring, inline documentation, and intelligent search). Many code editors and IDEs support TypeScript either natively or with plug-ins.
TypeScript 是 Angular 的首选语言。要了解更多，参见 typescriptlang.org。
TypeScript is the preferred language for Angular development. Read more about TypeScript at typescriptlang.org.
Universal
用来帮 Angular 应用实现服务端渲染的工具。 当与应用集成在一起时，Universal 可以在服务端生成静态页面并用它们来响应来自浏览器的请求。 当浏览器正准备运行完整版应用的时候，这个初始的静态页可以用作一个可快速加载的占位符。
A tool for implementing server-side rendering of an Angular application. When integrated with an app, Universal generates and serves static pages on the server in response to requests from browsers. The initial static page serves as a fast-loading placeholder while the full application is being prepared for normal execution in the browser.
欲知详情，参见 Angular Universal: 服务端渲染。
To learn more, see Angular Universal: server-side rendering.
视图 (view)
view
视图是可显示元素的最小分组单位，它们会被同时创建和销毁。 Angular 在一个或多个指令 (directive) 的控制下渲染视图， 尤其是组件 (component) 指令及其模板 (template)。
The smallest grouping of display elements that can be created and destroyed together. Angular renders a view under the control of one or more directives, especially component directives and their companion templates.
具体实现上，视图由一个与该组件相关的 ViewRef 实例表示。 属于某个组件的视图叫做宿主视图。 通常会把视图组织成一些视图树（view hierarchies）。
A view is specifically represented by a ViewRef instance associated with the component. A view that belongs to a component is called a host view. Views are typically collected into view hierarchies.
视图中各个元素的属性可以动态修改以响应用户的操作，而这些元素的结构（数量或顺序）则不能。你可以通过在它们的视图容器中插入、移动或移除内嵌视图来修改这些元素的结构。
Properties of elements in a view can change dynamically, in response to user actions; the structure (number and order) of elements in a view can't. You can change the structure of elements by inserting, moving, or removing nested views within their view containers.
当用户在应用中导航时（比如使用路由器），视图树可以动态加载或卸载。
View hierarchies can be loaded and unloaded dynamically as the user navigates through the application, typically under the control of a router.
视图引擎（View Engine）
View Engine
Angular 9 之前的版本使用的编译和渲染管道。可对比 Ivy。
The compilation and rendering pipeline used by Angular before version 9. Compare Ivy.
视图树（View hierarchy）
view hierarchy
一棵相关视图的树，它们可以作为一个整体行动。其根视图就是组件的宿主视图。宿主视图可以是内嵌视图树的根，它被收集到了宿主组件上的一个视图容器（ViewContainerRef）中。视图树是 Angular 变更检测的关键部件之一。
A tree of related views that can be acted on as a unit. The root view is a component's host view. A host view can be the root of a tree of embedded views, collected in a view container (ViewContainerRef) attached to an anchor element in the hosting component. The view hierarchy is a key part of Angular change detection.
视图树和组件树并不是一一对应的。那些嵌入到指定视图树上下文中的视图也可能是其它组件的宿主视图。那些组件可能和宿主组件位于同一个 NgModule 中，也可能属于其它 NgModule。
The view hierarchy doesn't imply a component hierarchy. Views that are embedded in the context of a particular hierarchy can be host views of other components. Those components can be in the same NgModule as the hosting component, or belong to other NgModules.
Web 组件
web component
参见自定义元素
See custom element.
工作空间（Workspace）
workspace
一组基于 Angular CLI 的 Angular 项目（也就是说应用或库），它们通常共同位于一个单一的源码仓库（比如 git）中。
A collection of Angular projects (that is, applications and libraries) powered by the Angular CLI that are typically co-located in a single source-control repository (such as git).
CLI 的 ng new 命令会在文件系统中创建一个目录（也就是工作空间的根目录）。 在工作空间根目录下，还会创建此工作空间的配置文件（angular.json），并且还会默认初始化一个同名的应用项目。
The CLI ng new command creates a file system directory (the "workspace root"). In the workspace root, it also creates the workspace configuration file (angular.json) and, by default, an initial application project with the same name.
而用来创建或操作应用和库的命令（比如 add 和 generate）必须在工作区目录下才能执行。
Commands that create or operate on apps and libraries (such as add and generate) must be executed from within a workspace folder.
欲知详情，参见工作空间配置。
For more information, see Workspace Configuration.
工作空间配置（Workspace configuration）
workspace configuration
一个名叫 angular.json 的文件，它位于 Angular 工作空间 的根目录下，并为 Angular CLI 提供的或集成的各个构建/开发工具提供工作空间级和项目专属的默认配置项。
A file named angular.json at the root level of an Angular workspace provides workspace-wide and project-specific configuration defaults for build and development tools that are provided by or integrated with the Angular CLI.
欲知详情，参见工作空间配置。
For more information, see Workspace Configuration.
还有一些项目专属的配置文件是给某些工具使用的。比如 package.json 是给 npm 包管理器使用的，tsconfig.json 是给 TypeScript 转译器使用的，而 tslint.json 是给 TSLint 使用的。
Additional project-specific configuration files are used by tools, such as package.json for the npm package manager, tsconfig.json for TypeScript transpilation, and tslint.json for TSLint.
欲知详情，参见工作空间和项目文件结构。
For more information, see Workspace and Project File Structure.
区域 (zone)
zone
一组异步任务的执行上下文。它对于调试、性能分析和测试那些包含了异步操作（如事件处理、承诺、远程服务器调用等）的应用是非常有用的。
An execution context for a set of asynchronous tasks. Useful for debugging, profiling, and testing apps that include asynchronous operations such as event processing, promises, and calls to remote servers.
Angular 应用会运行在一个 Zone 区域中，在这里，它可以对异步事件做出反应，可以通过检查数据变更、利用数据绑定 (data bindings) 来更新信息显示。
An Angular app runs in a zone where it can respond to asynchronous events by checking for data changes and updating the information it displays by resolving data bindings.
Zone 的使用方可以在异步操作完成之前或之后采取行动。
A zone client can take action before and after an async operation completes.
要了解更多，参见 Brian Ford 的视频。
Learn more about zones in this Brian Ford video.
