block includes
include _util-fns
- var _on_Plunkr = 'on Plunkr';
:marked
Angular applications are made of _components_.
Angular 应用是由*组件*组成的。
A _component_ is the combination of an HTML template and a component class that controls a portion of the screen. Here is an example of a component that displays a simple string:
*组件*由 HTML 模板和组件类组成，组件类控制视图。下面是一个显示简单字符串的组件:
+makeExample('app/app.component.ts')(format='.')
:marked
You can try this out without installing anything. Open the QuickStart example !{_on_Plunkr} in another tab
and follow along.
无需任何安装就可以试试它。在另一个浏览器标签页打开并跟随 Plunker 上的《快速起步》例子。
Every component begins with an `@Component` [!{_decorator}](glossary.html#!{_decorator} '"!{_decorator}" explained')
function that
takes a _metadata_ object. The metadata object describes how the HTML template and component class work together.
每个组件都以`@Component`[装饰器](glossary.html#!{_decorator} '"!{_decorator}" explained')函数开始，它接受一个_元数据_对象参数。该元素对象描述了 HTML 模板和组件类是如何一起工作的。
The `selector` property tells Angular to display the component inside a custom `` tag in the `index.html`.
`selector`属性为 Angular 指定了在`index.html`中的自定义``标签里显示该组件。
+makeExample('index.html','my-app','index.html (inside )')(format='.')
:marked
The `template` property defines a message inside an `` header.
The message starts with "Hello" and ends with `{{name}}`
which is an Angular [interpolation binding](guide/displaying-data.html) expression.
At runtime, Angular replaces `{{name}}` with the value of the component's `name` property.
`template`属性定义了``标题里的一条消息。
该消息以 “Hello” 开始，以 Angular [插值绑定](guide/displaying-data.html)表达式`{{name}}`结束。
在运行时，Angular 用组件的`name`属性值替换`{{name}}`。
In the example, change the component class's `name` property from `'Angular'` to `'World'` and see what happens.
在本例中，将组件类的`name`属性从`'Angular'`改为`'World'`，看看会发生什么。
Interpolation binding is one of many Angular features you'll discover in this documentation.
插值绑定是 Angular 的特征之一。你将在本文档中探索更多 Angular 的特征。
+ifDocsFor('ts')
.callout.is-helpful
header A word about TypeScript
header 关于 TypeScript
p.
This example is written in TypeScript, a superset of JavaScript. Angular
uses TypeScript because its types make it easy to support developer productivity with tooling. You can also write Angular code in JavaScript; this guide explains how.
p.
本例是用 JavaScript 的一个超集 TypeScript 编写的。
Angular 使用 TypeScript 是因为它的类型可以帮助工具提高开发者效率。你也可以用 JavaScript 编写 Angular 代码，参见本指南。
.l-sub-section
:marked
### Next step
### 下一步
To learn how to write a real application, your next step is to set up a local development
environment and begin exploring with code. The [**Developer Guide**](guide/index.html)
shows you how.
要学习如何编写应用，你的下一步是构建本地开发环境，并开始一边编程一边探索，参见[**开发者指南**](guide/index.html)。