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								{@a top}
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								# Set the Document Title
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								# 设置文档标题
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								Your app should be able to make the browser title bar say whatever you want it to say.
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								This cookbook explains how to do it.
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											2018-07-27 08:21:48 +08:00
										 
									 
								 
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								应用程序应该能让浏览器标题栏显示你想让它显示的内容。本文会解释怎么做。
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								See the <live-example name="set-document-title"></live-example>.
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								参见<live-example name="set-document-title"></live-example>
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											2017-02-22 18:09:39 +00:00
										 
									 
								 
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								## The problem with *<title>*
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								## *<title>*的问题
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								The obvious approach is to bind a property of the component to the HTML `<title>` like this:
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								显而易见的方法是把组件的属性绑定到 HTML 的 `<title>` 标签上,像这样:
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								<code-example format=''>
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								  <title>{{This_Does_Not_Work}}</title>
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								</code-example>
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								Sorry but that won't work.
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								The root component of the application is an element contained within the `<body>` tag.
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								The HTML `<title>` is in the document `<head>`, outside the body, making it inaccessible to Angular data binding.
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											2018-03-22 17:18:48 +08:00
										 
									 
								 
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								抱歉,这样不行。应用程序的根组件是一个包含在 `<body>` 标签里的元素。该 HTML 的 `<title>` 在文档的 `<head>` 元素里,在 `<body>` 之外,Angular 的数据绑定无法访问到它。
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								You could grab the browser `document` object and set the title manually.
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								That's dirty and undermines your chances of running the app outside of a browser someday.
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								可以从浏览器获得 `document` 对象,并且手动设置标题。但是这样看起来很脏,而且将无法在浏览器之外运行应用程序。
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								<div class="alert is-helpful">
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								  Running your app outside a browser means that you can take advantage of server-side
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								  pre-rendering for near-instant first app render times and for SEO.  It means you could run from
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								  inside a Web Worker to improve your app's responsiveness by using multiple threads.  And it
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								  means that you could run your app inside Electron.js or Windows Universal to deliver it to the desktop.
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								  在浏览器外运行应用程序意味着:利用服务器端预先渲染,为应用程序实现几乎实时的首次渲染,同时还能支持 SEO(搜索引擎优化)。
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								意味着你可以在一个 Web Worker 中运行你的应用程序,通过多线程技术增强应用程序的响应性。
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								还意味着你可以在 Electron.js 或者 Windows Universal 里面运行,发布到桌面环境。
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								</div>
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								## Use the `Title` service
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								## 使用 `Title` 服务
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								Fortunately, Angular bridges the gap by providing a `Title` service as part of the *Browser platform*.
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								The [Title](api/platform-browser/Title) service is a simple class that provides an API
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								for getting and setting the current HTML document title:
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								幸运的是,Angular 在*浏览器平台*的包中,提供了一个 `Title` 服务,弥补了这种差异。
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								[Title](api/platform-browser/Title)服务是一个简单的类,提供了一个 API,用来获取和设置当前 HTML 文档的标题。
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								* `getTitle() : string`—Gets the title of the current HTML document.
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								   `getTitle(): string` —— 获取当前 HTML 文档的标题。
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								* `setTitle( newTitle : string )`—Sets the title of the current HTML document.
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								   `setTitle( newTitle: string)` —— 设置当前 HTML 文档的标题。
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								You can inject the `Title` service into the root `AppComponent` and expose a bindable `setTitle` method that calls it:
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								你可以把 `Title` 服务注入到根组件 `AppComponent`,并暴露出可供绑定的 `setTitle` 方法让别人来调用该服务:
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								<code-example path="set-document-title/src/app/app.component.ts" region="class" header="src/app/app.component.ts (class)" linenums="false"></code-example>
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								Bind that method to three anchor tags and voilà!
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								把这个方法绑定到三个 A 标签,瞧瞧!
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											2017-05-09 23:53:32 +01:00
										 
									 
								 
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								<figure>
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								  <img src="generated/images/guide/set-document-title/set-title-anim.gif" alt="Set title">
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								</figure>
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								Here's the complete solution:
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								这里是完整的方案(代码)。
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											2017-03-27 16:08:53 +01:00
										 
									 
								 
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								<code-tabs>
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								  <code-pane header="src/main.ts" path="set-document-title/src/main.ts"></code-pane>
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								  <code-pane header="src/app/app.module.ts" path="set-document-title/src/app/app.module.ts"></code-pane>
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								  <code-pane header="src/app/app.component.ts" path="set-document-title/src/app/app.component.ts"></code-pane>
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								</code-tabs>
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								## Why provide the `Title` service in `bootstrap`
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								## 为什么要在 *bootstrap* 里面提供这个 *Title* 服务
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								Generally you want to provide application-wide services in the root application component, `AppComponent`.
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								你通常会在应用程序的根组件 `AppComponent` 中提供应用程序级的服务。
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								This cookbook recommends registering the title service during bootstrapping,
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								a location you reserve for configuring the runtime Angular environment.
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								但这里,要在引导过程中注册这个 Title 服务,这个位置是为你设置 Angular 运行环境而保留的。
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								That's exactly what you're doing.
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								The `Title` service is part of the Angular *browser platform*.
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								If you bootstrap your application into a different platform,
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								you'll have to provide a different `Title` service that understands
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								the concept of a "document title" for that specific platform.
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								Ideally, the application itself neither knows nor cares about the runtime environment.
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								你的做法正是如此。这里的 `Title` 服务是 Angular*浏览器平台*的一部分。如果在其它平台上引导应用程序,就得提供另一个专为那个平台准备的 `Title` 服务。
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