76 lines
3.1 KiB
Markdown
76 lines
3.1 KiB
Markdown
{@a top}
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# Set the Document Title
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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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See the <live-example name="set-document-title"></live-example>.
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## The problem with *<title>*
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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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<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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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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<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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</div>
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## Use the `Title` service
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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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* `getTitle() : string`—Gets the title of the current HTML document.
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* `setTitle( newTitle : string )`—Sets the title of the current HTML document.
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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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<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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<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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<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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Generally you want to provide application-wide services in the root application component, `AppComponent`.
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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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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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