91 lines
4.1 KiB
Plaintext
91 lines
4.1 KiB
Plaintext
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include ../_util-fns
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a(id='top')
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:marked
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Our app should be able to make the browser title bar say whatever we want it to say.
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This cookbook explains how to do it.
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:marked
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**See the [live example](/resources/live-examples/cb-set-document-title/ts/plnkr.html)**.
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.l-sub-section
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img(src='/resources/images/devguide/plunker-separate-window-button.png' alt="pop out the window" align="right" style="margin-right:-20px")
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:marked
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To see the browser Title bar changes,
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pop out the preview window by clicking the blue 'X' button in the upper right corner.
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:marked
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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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:marked
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Sorry but that won't work.
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The root component of our 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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We could grab the browser `document` object and set the title manually.
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That's dirty and undermines our chances of running the app outside of a browser someday.
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.l-sub-section
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:marked
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That's a major Angular architectural goal. It may not seem important to us right now.
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But why squander that future just to set the title bar?
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:marked
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## Use the *Title* service
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Fortunately, Angular 2 bridges the gap by providing a `Title` service as part of the *Browser platform*.
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The [Title](../api//platform/browser/Title-class.html) 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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While this class is part of the Browser platform package, it is *not part of the default Browser
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platform providers* that Angular loads automatically.
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This means as we bootstrap our application using the Browser platform `boostrap()`
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function, we'll also have to include `Title` service explicitly as one of the bootstrap providers:
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+makeExample( "cb-set-document-title/ts/app/main.ts", "bootstrap-title", "app/main.ts (provide Title service)" )(format='.')
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:marked
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Once we've explicitly provided the `Title` service we can then inject the `Title` service into any of our
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custom application components and services.
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Let's inject the `Title` service into the root `AppComponent` and expose a bindable `setTitle` method that calls it:
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+makeExample( "cb-set-document-title/ts/app/app.component.ts", "class", "app/app.component.ts (class)" )(format='.')
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:marked
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We bind that method to three anchor tags and, voilà!
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figure.image-display
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img(src="/resources/images/cookbooks/set-document-title/set-title-anim.gif" alt="Set title")
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:marked
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Here's the complete solution
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+makeTabs(
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`cb-set-document-title/ts/app/main.ts,
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cb-set-document-title/ts/app/app.component.ts`,
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'',
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'app/main.ts, app/app.component.ts' )
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//
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Todo: tie this back to the router so we can see how to use this Title service to (re)set the title
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that appears in the window navigation history and shows up in the back/forward buttons
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during routing.
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See https://github.com/angular/angular/issues/7630#issuecomment-198328802
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.l-main-section
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:marked
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## Why we provide the *Title* service in *bootstrap*
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We generally recommended providing application-wide services in the root application component, `AppComponent`.
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Here we recommend registering the title service during bootstrapping,
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a location we reserve for configuring the runtime Angular enviroment.
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That's exactly what we're doing.
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The `Title` service is part of the Angular *browser platform*.
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If we bootstrap our application into a different platform,
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we'll have to provide a different `Title` service that understands 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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:marked
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[Back to top](#top)
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