73 lines
2.7 KiB
Plaintext
73 lines
2.7 KiB
Plaintext
extends ../../../ts/_cache/guide/architecture.jade
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block includes
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include ../_util-fns
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- var _library_module = 'library'
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- var _at_angular = 'angular2'
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:marked
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Angular is a framework to help us build client applications in HTML and
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either JavaScript or a language (like Dart or TypeScript) that compiles to JavaScript.
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block angular-parts
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:marked
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Angular 2 for Dart is published as the `angular2` package, which
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(like many other Dart packages) is available via the Pub tool.
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block modules-in-dart
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.callout.is-helpful
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header Dart difference: Modules are compilation units or packages
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:marked
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In this guide, the term _module_ refers to a Dart compilation unit, such
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as a library, or a package. (If a Dart file has no `library` or `part`
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directive, then that file itself is a library and thus a compilation
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unit.) For more information about compilation units, see
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the chapter on "Libraries and Scripts" in the
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[Dart Language Specification](https://www.dartlang.org/docs/spec/).
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block modules-are-optional
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//- N/A
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block export-qualifier
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.callout.is-helpful
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header Dart difference: Public names are exported by default
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:marked
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Contrary to TypeScript, a Dart library always exports all names and
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declarations in its **public** namespace, making explicit `export`
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qualifiers unnecessary.
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When we say that a module _exports_ a declaration, we mean that the
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declaration is _public_. For more details about name spaces and export
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statements, see the section on "Exports" in the
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[Dart Language Specification](https://www.dartlang.org/docs/spec/).
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block ts-import
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//- N/A
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block angular-library-modules
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:marked
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Angular ships as a collection of libraries within the
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[**angular2**](https://pub.dartlang.org/packages/angular2) package.
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block angular-imports
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+makeExcerpt('app/app.component.ts', 'import')
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block ts-decorator
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:marked
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Annotations often have configuration parameters.
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The `@Component` annotation takes parameters to provide the
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information Angular needs to create and present the component and its view.
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Here are a few of the possible `@Component` parameters:
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block dart-bool
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.callout.is-helpful
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header Dart difference: Only true is true
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:marked
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In Dart, **the only value that is true is the boolean value `true`**; all
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other values are false. JavaScript and TypeScript, in contrast, treat values
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such as 1 and most non-null objects as true. For this reason, the JavaScript
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and TypeScript versions of this app can use just `selectedHero` as the value
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of the `*ngIf` expression. The Dart version must use a boolean operator such
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as `!=` instead.
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