从 AngularJS 升级到 Angularlink

Upgrading from AngularJS to Angularlink

Angular 这个名字专指现在和未来的 Angular 版本，而 AngularJS 专指 Angular 的所有 1.x 版本。

Angular is the name for the Angular of today and tomorrow.
AngularJS is the name for all 1.x versions of Angular.

有很多大型 AngularJS 应用。 在决定迁移到 Angular 之前，首先要深入思考业务案例。 在这些案例中，最重要的部分之一是时间和需要付出的努力。 本章描述用于把 AngularJS 应用高效迁移到 Angular 平台的内置工具，每次讲一点点。

AngularJS apps are great. Always consider the business case before moving to Angular. An important part of that case is the time and effort to get there. This guide describes the built-in tools for efficiently migrating AngularJS projects over to the Angular platform, a piece at a time.

有些应用可能比其它的升级起来简单，还有一些方法能让把这项工作变得更简单。 即使在正式开始升级过程之前，可以提前准备 AngularJS 的程序，让它向 Angular 看齐。 这些准备步骤几乎都是关于如何让代码更加松耦合、更有可维护性，以及用现代开发工具提高速度的。 这意味着，这种准备工作不仅能让最终的升级变得更简单，而且还能提升 AngularJS 程序的质量。

Some applications will be easier to upgrade than others, and there are many ways to make it easier for yourself. It is possible to prepare and align AngularJS applications with Angular even before beginning the upgrade process. These preparation steps are all about making the code more decoupled, more maintainable, and better aligned with modern development tools. That means in addition to making the upgrade easier, you will also improve the existing AngularJS applications.

成功升级的关键之一是增量式的实现它，通过在同一个应用中一起运行这两个框架，并且逐个把 AngularJS 的组件迁移到 Angular 中。 这意味着可以在不必打断其它业务的前提下，升级更大、更复杂的应用程序，因为这项工作可以多人协作完成，在一段时间内逐渐铺开。 Angular upgrade 模块的设计目标就是让你渐进、无缝的完成升级。

One of the keys to a successful upgrade is to do it incrementally, by running the two frameworks side by side in the same application, and porting AngularJS components to Angular one by one. This makes it possible to upgrade even large and complex applications without disrupting other business, because the work can be done collaboratively and spread over a period of time. The upgrade module in Angular has been designed to make incremental upgrading seamless.

准备工作link

Preparationlink

AngularJS 应用程序的组织方式有很多种。当你想把它们升级到 Angular 的时候， 有些做起来会比其它的更容易些。即使在开始升级之前，也有一些关键的技术和模式可以让你将来升级时更轻松。

There are many ways to structure AngularJS applications. When you begin to upgrade these applications to Angular, some will turn out to be much more easy to work with than others. There are a few key techniques and patterns that you can apply to future proof apps even before you begin the migration.

遵循 AngularJS 风格指南link

Follow the AngularJS Style Guidelink

AngularJS 风格指南收集了一些已证明能写出干净且可维护的 AngularJS 程序的模式与实践。 它包含了很多关于如何书写和组织 AngularJS 代码的有价值信息，同样重要的是，不应该采用的书写和组织 AngularJS 代码的方式。

The AngularJS Style Guide collects patterns and practices that have been proven to result in cleaner and more maintainable AngularJS applications. It contains a wealth of information about how to write and organize AngularJS code - and equally importantly - how not to write and organize AngularJS code.

Angular 是一个基于 AngularJS 中最好的部分构思出来的版本。在这种意义上，它的目标和 AngularJS 风格指南是一样的： 保留 AngularJS 中好的部分，去掉坏的部分。当然，Angular 还做了更多。 说这些的意思是：遵循这个风格指南可以让你写出更接近 Angular 程序的 AngularJS 程序。

Angular is a reimagined version of the best parts of AngularJS. In that sense, its goals are the same as the AngularJS Style Guide's: To preserve the good parts of AngularJS, and to avoid the bad parts. There's a lot more to Angular than just that of course, but this does mean that following the style guide helps make your AngularJS app more closely aligned with Angular.

有一些特别的规则可以让使用 Angular 的 upgrade/static 模块进行增量升级变得更简单：

There are a few rules in particular that will make it much easier to do an incremental upgrade using the Angular upgrade/static module:

• 单一规则 规定每个文件应该只放一个组件。这不仅让组件更容易浏览和查找，而且还让你能逐个迁移它们的语言和框架。 在这个范例程序中，每个控制器、工厂和过滤器都位于各自的源文件中。

  The Rule of 1 states that there should be one component per file. This not only makes components easy to navigate and find, but will also allow us to migrate them between languages and frameworks one at a time. In this example application, each controller, component, service, and filter is in its own source file.

• 按特性分目录的结构和模块化规则在较高的抽象层定义了一些相似的原则：应用程序中的不同部分应该被分到不同的目录和 NgModule 中。

  The Folders-by-Feature Structure and Modularity rules define similar principles on a higher level of abstraction: Different parts of the application should reside in different directories and NgModules.

如果应用程序能用这种方式把每个特性分到一个独立目录中，它也就能每次迁移一个特性。 对于那些还没有这么做的程序，强烈建议把应用这条规则作为准备步骤。而且这也不仅仅对升级有价值， 它还是一个通用的规则，可以让你的程序更“坚实”。

When an application is laid out feature per feature in this way, it can also be migrated one feature at a time. For applications that don't already look like this, applying the rules in the AngularJS style guide is a highly recommended preparation step. And this is not just for the sake of the upgrade - it is just solid advice in general!

使用模块加载器link

Using a Module Loaderlink

当你把应用代码分解到每个文件中只放一个组件的粒度后，通常会得到一个由大量相对较小的文件组成的项目结构。 这比组织成少量大文件要整洁得多，但如果你不得不通过 <script> 标签在 HTML 页面中加载所有这些文件，那就不好玩了。 尤其是当你不得不自己按正确的顺序维护这些标签时更是如此，就要开始使用模块加载器了。

When you break application code down into one component per file, you often end up with a project structure with a large number of relatively small files. This is a much neater way to organize things than a small number of large files, but it doesn't work that well if you have to load all those files to the HTML page with <script> tags. Especially when you also have to maintain those tags in the correct order. That's why it's a good idea to start using a module loader.

使用模块加载器，比如SystemJS、 Webpack或Browserify， 可以让你在程序中使用 TypeScript 或 ES2015 语言内置的模块系统。 你可以使用 import 和 export 特性来明确指定哪些代码应该以及将会被在程序的不同部分之间共享。 对于 ES5 程序来说，可以改用 CommonJS 风格的 require 和 module.exports 特性代替。 无是论哪种情况，模块加载器都会按正确的顺序加载程序中用到的所有代码。

Using a module loader such as SystemJS, Webpack, or Browserify allows us to use the built-in module systems of TypeScript or ES2015. You can use the import and export features that explicitly specify what code can and will be shared between different parts of the application. For ES5 applications you can use CommonJS style require and module.exports features. In both cases, the module loader will then take care of loading all the code the application needs in the correct order.

当要把应用程序投入生产环境时，模块加载器也会让你把所有这些文件打成完整的产品包变得容易一些。

When moving applications into production, module loaders also make it easier to package them all up into production bundles with batteries included.

迁移到 TypeScriptlink

Migrating to TypeScriptlink

Angular 升级计划的一部分是引入 TypeScript，即使在开始升级之前，引入 TypeScript 编译器也是有意义的。 这意味着等真正升级的时候需要学习和思考的东西会更少，并且你可以在 AngularJS 代码中开始使用 TypeScript 的特性。

If part of the Angular upgrade plan is to also take TypeScript into use, it makes sense to bring in the TypeScript compiler even before the upgrade itself begins. This means there's one less thing to learn and think about during the actual upgrade. It also means you can start using TypeScript features in your AngularJS code.

TypeScript 是 ECMAScript 2015 的超集，而 ES2015 又是 ECMAScript 5 的超集。 这意味着除了安装一个 TypeScript 编译器，并把文件名都从 *.js 改成 *.ts 之外，其实什么都不用做。 当然，如果仅仅这样做也没什么大用，也没什么有意思的地方。 下面这些额外的步骤可以让你打起精神：

Since TypeScript is a superset of ECMAScript 2015, which in turn is a superset of ECMAScript 5, "switching" to TypeScript doesn't necessarily require anything more than installing the TypeScript compiler and renaming files from *.js to *.ts. But just doing that is not hugely useful or exciting, of course. Additional steps like the following can give us much more bang for the buck:

• 对那些使用了模块加载器的程序，TypeScript 的导入和导出语法(实际上是 ECMAScript 2015 的导入和导出)可以把代码组织成模块。

  For applications that use a module loader, TypeScript imports and exports (which are really ECMAScript 2015 imports and exports) can be used to organize code into modules.

• 可以逐步把类型注解添加到现有函数和变量上，以固定它们的类型，并获得其优点：比如编译期错误检查、更好的支持自动完成，以及内联式文档等。

  Type annotations can be gradually added to existing functions and variables to pin down their types and get benefits like build-time error checking, great autocompletion support and inline documentation.

• 那些 ES2015 中新增的特性，比如箭头函数、let、const、默认函数参数、解构赋值等也可以逐渐添加进来，让代码更有表现力。

  JavaScript features new to ES2015, like arrow functions, lets and consts, default function parameters, and destructuring assignments can also be gradually added to make the code more expressive.

• 服务和控制器可以转成类。这样它们就能一步步接近 Angular 的服务和组件类了，也会让升级变得简单一点。

  Services and controllers can be turned into classes. That way they'll be a step closer to becoming Angular service and component classes, which will make life easier after the upgrade.

使用组件型指令link

Using Component Directiveslink

在 Angular 中，组件是用来构建用户界面的主要元素。你把 UI 中的不同部分定义成组件，然后在模板中使用这些组件合成出最终的 UI。

In Angular, components are the main primitive from which user interfaces are built. You define the different portions of the UI as components and compose them into a full user experience.

你在 AngularJS 中也能这么做。那就是一种定义了自己的模板、控制器和输入/输出绑定的指令 —— 跟 Angular 中对组件的定义是一样的。 要迁移到 Angular，通过组件型指令构建的应用程序会比直接用 ng-controller、ng-include 和作用域继承等底层特性构建的要容易得多。

You can also do this in AngularJS, using component directives. These are directives that define their own templates, controllers, and input/output bindings - the same things that Angular components define. Applications built with component directives are much easier to migrate to Angular than applications built with lower-level features like ng-controller, ng-include, and scope inheritance.

要与 Angular 兼容，AngularJS 的组件型指令应该配置下列属性：

To be Angular compatible, an AngularJS component directive should configure these attributes:

• restrict: 'E'。组件通常会以元素的方式使用。

  restrict: 'E'. Components are usually used as elements.

• scope: {} - 一个独立作用域。在 Angular 中，组件永远是从它们的环境中被隔离出来的，在 AngularJS 中也同样如此。

  scope: {} - an isolate scope. In Angular, components are always isolated from their surroundings, and you should do this in AngularJS too.

• bindToController: {}。组件的输入和输出应该绑定到控制器，而不是 $scope。

  bindToController: {}. Component inputs and outputs should be bound to the controller instead of using the $scope.

• controller 和 controllerAs。组件要有自己的控制器。

  controller and controllerAs. Components have their own controllers.

• template 或 templateUrl。组件要有自己的模板。

  template or templateUrl. Components have their own templates.

组件型指令还可能使用下列属性：

Component directives may also use the following attributes:

• transclude: true：如果组件需要从其它地方透传内容，就设置它。

  transclude: true/{}, if the component needs to transclude content from elsewhere.

• require：如果组件需要和父组件的控制器通讯，就设置它。

  require, if the component needs to communicate with some parent component's controller.

组件型指令不能使用下列属性：

Component directives should not use the following attributes:

• compile。Angular 不再支持它。

  compile. This will not be supported in Angular.

• replace: true。Angular 永远不会用组件模板替换一个组件元素。这个特性在 AngularJS 中也同样不建议使用了。

  replace: true. Angular never replaces a component element with the component template. This attribute is also deprecated in AngularJS.

• priority 和 terminal。虽然 AngularJS 的组件可能使用这些，但它们在 Angular 中已经没用了，并且最好不要再写依赖它们的代码。

  priority and terminal. While AngularJS components may use these, they are not used in Angular and it is better not to write code that relies on them.

AngularJS 中一个完全向 Angular 架构对齐过的组件型指令是这样的：

An AngularJS component directive that is fully aligned with the Angular architecture may look something like this:

      
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export function heroDetailDirective() {
  return {
    restrict: 'E',
    scope: {},
    bindToController: {
      hero: '=',
      deleted: '&'
    },
    template: `
      <h2>{{$ctrl.hero.name}} details!</h2>
      <div><label>id: </label>{{$ctrl.hero.id}}</div>
      <button ng-click="$ctrl.onDelete()">Delete</button>
    `,
    controller: function() {
      this.onDelete = () => {
        this.deleted({hero: this.hero});
      };
    },
    controllerAs: '$ctrl'
  };
}
    

AngularJS 1.5 引入了组件 API，它让定义指令变得更简单了。 为组件型指令使用这个 API 是一个好主意，因为：

AngularJS 1.5 introduces the component API that makes it easier to define component directives like these. It is a good idea to use this API for component directives for several reasons:

• 它需要更少的样板代码。

  It requires less boilerplate code.

• 它强制你遵循组件的最佳实践，比如 controllerAs。

  It enforces the use of component best practices like controllerAs.

• 指令中像 scope 和 restrict 这样的属性应该有良好的默认值。

  It has good default values for directive attributes like scope and restrict.

如果使用这个组件 API 进行表示，那么上面看到的组件型指令就变成了这样：

The component directive example from above looks like this when expressed using the component API:

      
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export const heroDetail = {
  bindings: {
    hero: '<',
    deleted: '&'
  },
  template: `
    <h2>{{$ctrl.hero.name}} details!</h2>
    <div><label>id: </label>{{$ctrl.hero.id}}</div>
    <button ng-click="$ctrl.onDelete()">Delete</button>
  `,
  controller: function() {
    this.onDelete = () => {
      this.deleted(this.hero);
    };
  }
};
    

控制器的生命周期钩子 $onInit()、$onDestroy() 和 $onChanges() 是 AngularJS 1.5 引入的另一些便利特性。 它们都很像Angular 中的等价物，所以，围绕它们组织组件生命周期的逻辑在升级到 Angular 时会更容易。

Controller lifecycle hook methods $onInit(), $onDestroy(), and $onChanges() are another convenient feature that AngularJS 1.5 introduces. They all have nearly exact equivalents in Angular, so organizing component lifecycle logic around them will ease the eventual Angular upgrade process.

使用升级适配器进行升级link

Upgrading with ngUpgradelink

不管要升级什么，Angular 中的 ngUpgrade 库都会是一个非常有用的工具 —— 除非是小到没功能的应用。 借助它，你可以在同一个应用程序中混用并匹配 AngularJS 和 Angular 的组件，并让它们实现无缝的互操作。 这意味着你不用被迫一次性做完所有的升级工作，因为在整个演进过程中，这两个框架可以很自然的和睦相处。

The ngUpgrade library in Angular is a very useful tool for upgrading anything but the smallest of applications. With it you can mix and match AngularJS and Angular components in the same application and have them interoperate seamlessly. That means you don't have to do the upgrade work all at once, since there's a natural coexistence between the two frameworks during the transition period.

升级模块工作原理link

How ngUpgrade Workslink

ngUpgrade 提供的主要工具之一被称为 UpgradeModule。这是一个服务，它可以启动并管理一个能同时支持 Angular 和 AngularJS 的混合式应用。

One of the primary tools provided by ngUpgrade is called the UpgradeModule. This is a module that contains utilities for bootstrapping and managing hybrid applications that support both Angular and AngularJS code.

当使用 ngUpgrade 时，你实际上在同时运行 AngularJS 和 Angular。所有 Angular 的代码运行在 Angular 框架中，而 AngularJS 的代码运行在 AngularJS 框架中。所有这些都是真实的、全功能的框架版本。 没有进行任何仿真，所以你可以认为同时存在着这两个框架的所有特性和自然行为。

When you use ngUpgrade, what you're really doing is running both AngularJS and Angular at the same time. All Angular code is running in the Angular framework, and AngularJS code in the AngularJS framework. Both of these are the actual, fully featured versions of the frameworks. There is no emulation going on, so you can expect to have all the features and natural behavior of both frameworks.

所有这些事情的背后，本质上是一个框架中管理的组件和服务能和来自另一个框架的进行互操作。 这些主要体现在三个方面：依赖注入、DOM 和变更检测。

What happens on top of this is that components and services managed by one framework can interoperate with those from the other framework. This happens in three main areas: Dependency injection, the DOM, and change detection.

依赖注入link

Dependency Injectionlink

无论是在 AngularJS 中还是在 Angular 中，依赖注入都位于前沿和中心的位置，但在两个框架的工作原理上，却存在着一些关键的不同之处。

Dependency injection is front and center in both AngularJS and Angular, but there are some key differences between the two frameworks in how it actually works.

就算有这么多不同点，也并不妨碍你在依赖注入时进行互操作。UpgradeModule 解决了这些差异，并让它们无缝的对接：

Even accounting for these differences you can still have dependency injection interoperability. upgrade/static resolves the differences and makes everything work seamlessly:

• 通过升级它们，你就能让那些在 AngularJS 中能被注入的服务也可用于 Angular 的代码中。 在框架之间共享的是服务的同一个单例对象。在 Angular 中，这些外来服务总是被放在根注入器中，并可用于所有组件。 它们总是具有字符串令牌 —— 跟它们在 AngularJS 中的令牌相同。

  You can make AngularJS services available for injection to Angular code by upgrading them. The same singleton instance of each service is shared between the frameworks. In Angular these services will always be in the root injector and available to all components.

• 通过降级它们，你也能让那些在 Angular 中能被注入的服务在 AngularJS 的代码中可用。 只有那些来自 Angular 根注入器的服务才能被降级。同样的，在框架之间共享的是同一个单例对象。 当你注册一个要降级的服务时，要明确指定一个打算在 AngularJS 中使用的字符串令牌。

  You can also make Angular services available for injection to AngularJS code by downgrading them. Only services from the Angular root injector can be downgraded. Again, the same singleton instances are shared between the frameworks. When you register a downgraded service, you must explicitly specify a string token that you want to use in AngularJS.

组件与 DOMlink

Components and the DOMlink

在混合式应用中，同时存在来自 AngularJS 和 Angular 中组件和指令的 DOM。 这些组件通过它们各自框架中的输入和输出绑定来互相通讯，它们由 UpgradeModule 桥接在一起。 它们也能通过共享被注入的依赖彼此通讯，就像前面所说的那样。

In the DOM of a hybrid ngUpgrade application are components and directives from both AngularJS and Angular. These components communicate with each other by using the input and output bindings of their respective frameworks, which ngUpgrade bridges together. They may also communicate through shared injected dependencies, as described above.

理解混合式应用的关键在于，DOM 中的每一个元素都只能属于这两个框架之一，而另一个框架则会忽略它。如果一个元素属于 AngularJS ，那么 Angular 就会当它不存在，反之亦然。

The key thing to understand about a hybrid application is that every element in the DOM is owned by exactly one of the two frameworks. The other framework ignores it. If an element is owned by AngularJS, Angular treats it as if it didn't exist, and vice versa.

所以，混合式应用总是像 AngularJS 程序那样启动，处理根模板的也是 AngularJS. 然后，当这个应用的模板中使用到了 Angular 的组件时，Angular 才开始参与。 这个组件的视图由 Angular 进行管理，而且它还可以使用一系列的 Angular 组件和指令。

So normally a hybrid application begins life as an AngularJS application, and it is AngularJS that processes the root template, e.g. the index.html. Angular then steps into the picture when an Angular component is used somewhere in an AngularJS template. That component's template will then be managed by Angular, and it may contain any number of Angular components and directives.

更进一步说，你可以按照需要，任意穿插使用这两个框架。 使用下面的两种方式之一，你可以在这两个框架之间自由穿梭：

Beyond that, you may interleave the two frameworks. You always cross the boundary between the two frameworks by one of two ways:

1. 通过使用来自另一个框架的组件：AngularJS 的模板中用到了 Angular 的组件，或者 Angular 的模板中使用了 AngularJS 的组件。

   By using a component from the other framework: An AngularJS template using an Angular component, or an Angular template using an AngularJS component.

2. 通过透传(transclude)或投影(project)来自另一个框架的内容。UpgradeModule 牵线搭桥，把 AngularJS 的透传概念和 Angular 的内容投影概念关联起来。

   By transcluding or projecting content from the other framework. ngUpgrade bridges the related concepts of AngularJS transclusion and Angular content projection together.

当你使用一个属于另一个框架的组件时，就会发生一次跨框架边界的切换。不过，这种切换只发生在该组件元素的子节点上。 考虑一个场景，你从 AngularJS 中使用一个 Angular 组件，就像这样：

Whenever you use a component that belongs to the other framework, a switch between framework boundaries occurs. However, that switch only happens to the elements in the template of that component. Consider a situation where you use an Angular component from AngularJS like this:

      
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      <a-component></a-component>
    

此时，<a-component> 这个 DOM 元素仍然由 AngularJS 管理，因为它是在 AngularJS 的模板中定义的。 这也意味着你可以往它上面添加别的 AngularJS 指令，却不能添加 Angular 的指令。 只有在 <a-component> 组件的模板中才是 Angular 的天下。同样的规则也适用于在 Angular 中使用 AngularJS 组件型指令的情况。

The DOM element <a-component> will remain to be an AngularJS managed element, because it's defined in an AngularJS template. That also means you can apply additional AngularJS directives to it, but not Angular directives. It is only in the template of the <a-component> where Angular steps in. This same rule also applies when you use AngularJS component directives from Angular.

变更检测link

Change Detectionlink

AngularJS 中的变更检测全是关于 scope.$apply() 的。在每个事件发生之后，scope.$apply() 就会被调用。 这或者由框架自动调用，或者在某些情况下由你自己的代码手动调用。

The scope.$apply() is how AngularJS detects changes and updates data bindings. After every event that occurs, scope.$apply() gets called. This is done either automatically by the framework, or manually by you.

在 Angular 中，事情有点不一样。虽然变更检测仍然会在每一个事件之后发生，却不再需要每次调用 scope.$apply() 了。 这是因为所有 Angular 代码都运行在一个叫做Angular zone的地方。 Angular 总是知道什么时候代码执行完了，也就知道了它什么时候应该触发变更检测。代码本身并不需要调用 scope.$apply() 或其它类似的东西。

In Angular things are different. While change detection still occurs after every event, no one needs to call scope.$apply() for that to happen. This is because all Angular code runs inside something called the Angular zone. Angular always knows when the code finishes, so it also knows when it should kick off change detection. The code itself doesn't have to call scope.$apply() or anything like it.

在这种混合式应用的案例中，UpgradeModule 在 AngularJS 的方法和 Angular 的方法之间建立了桥梁。发生了什么呢？

In the case of hybrid applications, the UpgradeModule bridges the AngularJS and Angular approaches. Here's what happens:

• 应用中发生的每件事都运行在 Angular 的 zone 里。 无论事件发生在 AngularJS 还是 Angular 的代码中，都是如此。 这个 zone 会在每个事件之后触发 Angular 的变更检测。

  Everything that happens in the application runs inside the Angular zone. This is true whether the event originated in AngularJS or Angular code. The zone triggers Angular change detection after every event.

• UpgradeModule 将在每一次离开 Angular zone 时调用 AngularJS 的 $rootScope.$apply()。这样也就同样会在每个事件之后触发 AngularJS 的变更检测。

  The UpgradeModule will invoke the AngularJS $rootScope.$apply() after every turn of the Angular zone. This also triggers AngularJS change detection after every event.

在实践中，你不用在自己的代码中调用 $apply()，而不用管这段代码是在 AngularJS 还是 Angular 中。 UpgradeModule 都替你做了。你仍然可以调用 $apply()，也就是说你不必从现有代码中移除此调用。 在混合式应用中，这些调用只会触发一次额外的 AngularJS 变更检测。

In practice, you do not need to call $apply(), regardless of whether it is in AngularJS on Angular. The UpgradeModule does it for us. You can still call $apply() so there is no need to remove such calls from existing code. Those calls just trigger additional AngularJS change detection checks in a hybrid application.

当你降级一个 Angular 组件，然后把它用于 AngularJS 中时，组件的输入属性就会被 AngularJS 的变更检测体系监视起来。 当那些输入属性发生变化时，组件中相应的属性就会被设置。你也能通过实现OnChanges 接口来挂钩到这些更改，就像它未被降级时一样。

When you downgrade an Angular component and then use it from AngularJS, the component's inputs will be watched using AngularJS change detection. When those inputs change, the corresponding properties in the component are set. You can also hook into the changes by implementing the OnChanges interface in the component, just like you could if it hadn't been downgraded.

相应的，当你把 AngularJS 的组件升级给 Angular 使用时，在这个组件型指令的 scope(或 bindToController)中定义的所有绑定， 都将被挂钩到 Angular 的变更检测体系中。它们将和标准的 Angular 输入属性被同等对待，并当它们发生变化时设置回 scope(或控制器)上。

Correspondingly, when you upgrade an AngularJS component and use it from Angular, all the bindings defined for the component directive's scope (or bindToController) will be hooked into Angular change detection. They will be treated as regular Angular inputs. Their values will be written to the upgraded component's scope (or controller) when they change.

通过 Angular 的 NgModule 来使用 UpgradeModulelink

Using UpgradeModule with Angular NgModuleslink

AngularJS 还是 Angular 都有自己的模块概念，来帮你把应用组织成一些内聚的功能块。

Both AngularJS and Angular have their own concept of modules to help organize an application into cohesive blocks of functionality.

它们在架构和实现的细节上有着显著的不同。 在 AngularJS 中，你要把 AngularJS 的资源添加到 angular.module 属性上。 在 Angular 中，你要创建一个或多个带有 NgModule 装饰器的类，这些装饰器用来在元数据中描述 Angular 资源。差异主要来自这里。

Their details are quite different in architecture and implementation. In AngularJS, you add Angular assets to the angular.module property. In Angular, you create one or more classes adorned with an NgModule decorator that describes Angular assets in metadata. The differences blossom from there.

在混合式应用中，你同时运行了两个版本的 Angular。 这意味着你至少需要 AngularJS 和 Angular 各提供一个模块。 当你使用 AngularJS 的模块进行引导时，就得把 Angular 的模块传给 UpgradeModule。

In a hybrid application you run both versions of Angular at the same time. That means that you need at least one module each from both AngularJS and Angular. You will import UpgradeModule inside the NgModule, and then use it for bootstrapping the AngularJS module.

引导混合式应用程序link

Bootstrapping hybrid applicationslink

要想引导混合式应用，就必须在应用中分别引导 Angular 和 AngularJS 应用的一部分。你必须先引导 Angular ，然后再调用 UpgradeModule 来引导 AngularJS。

To bootstrap a hybrid application, you must bootstrap each of the Angular and AngularJS parts of the application. You must bootstrap the Angular bits first and then ask the UpgradeModule to bootstrap the AngularJS bits next.

在 AngularJS 应用中有一个 AngularJS 的根模块，它用于引导 AngularJS 应用。

In an AngularJS application you have a root AngularJS module, which will also be used to bootstrap the AngularJS application.

      
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      angular.module('heroApp', [])
  .controller('MainCtrl', function() {
    this.message = 'Hello world';
  });
    

单纯的 AngularJS 应用可以在 HTML 页面中使用 ng-app 指令进行引导，但对于混合式应用你要通过 UpgradeModule 模块进行手动引导。因此，在切换成混合式应用之前，最好先把 AngularJS 改写成使用 angular.bootstrap进行手动引导的方式。

Pure AngularJS applications can be automatically bootstrapped by using an ng-app directive somewhere on the HTML page. But for hybrid applications, you manually bootstrap via the UpgradeModule. Therefore, it is a good preliminary step to switch AngularJS applications to use the manual JavaScript angular.bootstrapmethod even before switching them to hybrid mode.

比如你现在有这样一个通过 ng-app 进行引导的应用：

Say you have an ng-app driven bootstrap such as this one:

      
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<!DOCTYPE HTML>
<html lang="en">
  <head>
    <base href="/">
    <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.5.3/angular.js"></script>
    <script src="app/ajs-ng-app/app.module.js"></script>
  </head>
 
  <body ng-app="heroApp" ng-strict-di>
    <div id="message" ng-controller="MainCtrl as mainCtrl">
      {{ mainCtrl.message }}
    </div>
  </body>
</html>
    

你可以从 HTML 中移除 ng-app 和 ng-strict-di 指令，改为从 JavaScript 中调用 angular.bootstrap，它能达到同样效果：

You can remove the ng-app and ng-strict-di directives from the HTML and instead switch to calling angular.bootstrap from JavaScript, which will result in the same thing:

      
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      angular.bootstrap(document.body, ['heroApp'], { strictDi: true });
    

要想把 AngularJS 应用变成 Hybrid 应用，就要先加载 Angular 框架。 根据 搭建本地开发环境中给出的步骤，选择性的把“快速上手”的 Github 仓库中的代码复制过来。

To begin converting your AngularJS application to a hybrid, you need to load the Angular framework. You can see how this can be done with SystemJS by following the instructions in Setup, selectively copying code from the QuickStart github repository.

也可以通过 npm install @angular/upgrade --save 命令来安装 @angular/upgrade 包，并给它添加一个到 @angular/upgrade/static 包的映射。

You also need to install the @angular/upgrade package via npm install @angular/upgrade --save and add a mapping for the @angular/upgrade/static package:

      
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      '@angular/upgrade/static': 'npm:@angular/upgrade/bundles/upgrade-static.umd.js',
    

接下来，创建一个 app.module.ts 文件，并添加下列 NgModule 类：

Next, create an app.module.ts file and add the following NgModule class:

      
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import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { UpgradeModule } from '@angular/upgrade/static';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ]
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.body, ['heroApp'], { strictDi: true });
  }
}
    

最小化的 NgModule 导入了 BrowserModule，它是每个基于浏览器的 Angular 应用必备的。 它还从 @angular/upgrade/static 中导入了 UpgradeModule，它导出了一些服务提供商，这些提供商会用于升级、降级服务和组件。

This bare minimum NgModule imports BrowserModule, the module every Angular browser-based app must have. It also imports UpgradeModule from @angular/upgrade/static, which exports providers that will be used for upgrading and downgrading services and components.

在 AppModule 的构造函数中，使用依赖注入技术获取了一个 UpgradeModule 实例，并用它在 AppModule.ngDoBootstrap 方法中启动 AngularJS 应用。 upgrade.bootstrap 方法接受和 angular.bootstrap 完全相同的参数。

In the constructor of the AppModule, use dependency injection to get a hold of the UpgradeModule instance, and use it to bootstrap the AngularJS app in the AppModule.ngDoBootstrap method. The upgrade.bootstrap method takes the exact same arguments as angular.bootstrap:

现在，你就可以使用 platformBrowserDynamic.bootstrapModule 方法来启动 AppModule 了。

Now you can bootstrap AppModule using the platformBrowserDynamic.bootstrapModule method.

      
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      import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

platformBrowserDynamic().bootstrapModule(AppModule);
    

恭喜！你就要开始运行这个混合式应用了！所有现存的 AngularJS 代码会像以前一样正常工作，但是你现在也同样可以运行 Angular 代码了。

Congratulations! You're running a hybrid application! The existing AngularJS code works as before and you're ready to start adding Angular code.

在 AngularJS 的代码中使用 Angular 的组件link

Using Angular Components from AngularJS Codelink

一旦你开始运行混合式应用，你就可以开始逐渐升级代码了。一种更常见的工作模式就是在 AngularJS 的上下文中使用 Angular 的组件。 该组件可能是全新的，也可能是把原本 AngularJS 的组件用 Angular 重写而成的。

Once you're running a hybrid app, you can start the gradual process of upgrading code. One of the more common patterns for doing that is to use an Angular component in an AngularJS context. This could be a completely new component or one that was previously AngularJS but has been rewritten for Angular.

假设你有一个简单的用来显示英雄信息的 Angular 组件：

Say you have a simple Angular component that shows information about a hero:

      
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      import { Component } from '@angular/core';

@Component({
  selector: 'hero-detail',
  template: `
    <h2>Windstorm details!</h2>
    <div><label>id: </label>1</div>
  `
})
export class HeroDetailComponent { }
    

如果你想在 AngularJS 中使用这个组件，就得用 downgradeComponent() 方法把它降级。 其结果是一个 AngularJS 的指令，你可以把它注册到 AngularJS 的模块中：

If you want to use this component from AngularJS, you need to downgrade it using the downgradeComponent() method. The result is an AngularJS directive, which you can then register in the AngularJS module:

      
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      import { HeroDetailComponent } from './hero-detail.component';

/* . . . */

import { downgradeComponent } from '@angular/upgrade/static';

angular.module('heroApp', [])
  .directive(
    'heroDetail',
    downgradeComponent({ component: HeroDetailComponent }) as angular.IDirectiveFactory
  );
    

由于 HeroDetailComponent 是一个 Angular 组件，所以你必须同时把它加入 AppModule 的 declarations 字段中。

Because HeroDetailComponent is an Angular component, you must also add it to the declarations in the AppModule.

并且由于这个组件在 AngularJS 模块中使用，也是你 Angular 应用的一个入口点，你还需要 将它加入到 NgModule 的 entryComponents 列表中。

And because this component is being used from the AngularJS module, and is an entry point into the Angular application, you must add it to the entryComponents for the NgModule.

      
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import { HeroDetailComponent } from './hero-detail.component';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  declarations: [
    HeroDetailComponent
  ],
  entryComponents: [
    HeroDetailComponent
  ]
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.body, ['heroApp'], { strictDi: true });
  }
}
    

最终的结果是一个叫做 heroDetail 的 AngularJS 指令，你可以像用其它指令一样把它用在 AngularJS 模板中。

The net result is an AngularJS directive called heroDetail, that you can use like any other directive in AngularJS templates.

      
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      <hero-detail></hero-detail>
    

当然，大多数组件都不像这个这么简单。它们中很多都有输入属性和输出属性，来把它们连接到外部世界。 Angular 的英雄详情组件带有像这样的输入属性与输出属性：

Most components are not quite this simple, of course. Many of them have inputs and outputs that connect them to the outside world. An Angular hero detail component with inputs and outputs might look like this:

      
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import { Component, EventEmitter, Input, Output } from '@angular/core';
import { Hero } from '../hero';
 
@Component({
  selector: 'hero-detail',
  template: `
    <h2>{{hero.name}} details!</h2>
    <div><label>id: </label>{{hero.id}}</div>
    <button (click)="onDelete()">Delete</button>
  `
})
export class HeroDetailComponent {
  @Input() hero: Hero;
  @Output() deleted = new EventEmitter<Hero>();
  onDelete() {
    this.deleted.emit(this.hero);
  }
}
    

这些输入属性和输出属性的值来自于 AngularJS 的模板，而 downgradeComponent() 方法负责桥接它们：

These inputs and outputs can be supplied from the AngularJS template, and the downgradeComponent() method takes care of wiring them up:

      
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      <div ng-controller="MainController as mainCtrl">
  <hero-detail [hero]="mainCtrl.hero"
               (deleted)="mainCtrl.onDelete($event)">
  </hero-detail>
</div>
    

注意，虽然你正在 AngularJS 的模板中，但却在使用 Angular 的属性(Attribute)语法来绑定到输入属性与输出属性。 这是降级的组件本身要求的。而表达式本身仍然是标准的 AngularJS 表达式。

Note that even though you are in an AngularJS template, you're using Angular attribute syntax to bind the inputs and outputs. This is a requirement for downgraded components. The expressions themselves are still regular AngularJS expressions.

      
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      [myHero]="hero"
    

      
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      [my-hero]="hero"
    

$event 变量能被用在输出属性里，以访问这个事件所发出的对象。这个案例中它是 Hero 对象，因为 this.deleted.emit() 函数曾把它传了出来。

The $event variable can be used in outputs to gain access to the object that was emitted. In this case it will be the Hero object, because that is what was passed to this.deleted.emit().

由于这是一个 AngularJS 模板，虽然它已经有了 Angular 中绑定的属性(Attribute)，你仍可以在这个元素上使用其它 AngularJS 指令。 例如，你可以用 ng-repeat 简单的制作该组件的多份拷贝：

Since this is an AngularJS template, you can still use other AngularJS directives on the element, even though it has Angular binding attributes on it. For example, you can easily make multiple copies of the component using ng-repeat:

      
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      <div ng-controller="MainController as mainCtrl">
  <hero-detail [hero]="hero"
               (deleted)="mainCtrl.onDelete($event)"
               ng-repeat="hero in mainCtrl.heroes">
  </hero-detail>
</div>
    

从 Angular 代码中使用 AngularJS 组件型指令link

Using AngularJS Component Directives from Angular Codelink

现在，你已经能在 Angular 中写一个组件，并把它用于 AngularJS 代码中了。 当你从低级组件开始移植，并往上走时，这非常有用。但在另外一些情况下，从相反的方向进行移植会更加方便： 从高级组件开始，然后往下走。这也同样能用 UpgradeModule 完成。 你可以升级AngularJS 组件型指令，然后从 Angular 中用它们。

So, you can write an Angular component and then use it from AngularJS code. This is useful when you start to migrate from lower-level components and work your way up. But in some cases it is more convenient to do things in the opposite order: To start with higher-level components and work your way down. This too can be done using the upgrade/static. You can upgrade AngularJS component directives and then use them from Angular.

不是所有种类的 AngularJS 指令都能升级。该指令必须是一个严格的组件型指令，具有上面的准备指南中描述的那些特征。 确保兼容性的最安全的方式是 AngularJS 1.5 中引入的组件 API。

Not all kinds of AngularJS directives can be upgraded. The directive really has to be a component directive, with the characteristics described in the preparation guide above. The safest bet for ensuring compatibility is using the component API introduced in AngularJS 1.5.

可升级组件的简单例子是只有一个模板和一个控制器的指令：

A simple example of an upgradable component is one that just has a template and a controller:

      
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      export const heroDetail = {
  template: `
    <h2>Windstorm details!</h2>
    <div><label>id: </label>1</div>
  `,
  controller: function() {
  }
};
    

你可以使用 UpgradeComponent 方法来把这个组件升级到 Angular。 具体方法是创建一个 Angular指令，继承 UpgradeComponent，在其构造函数中进行 super 调用， 这样你就得到一个完全升级的 AngularJS 组件，并且可以 Angular 中使用。 剩下是工作就是把它加入到 AppModule 的 declarations 数组。

You can upgrade this component to Angular using the UpgradeComponent class. By creating a new Angular directive that extends UpgradeComponent and doing a super call inside its constructor, you have a fully upgraded AngularJS component to be used inside Angular. All that is left is to add it to AppModule's declarations array.

      
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      import { Directive, ElementRef, Injector, SimpleChanges } from '@angular/core';
import { UpgradeComponent } from '@angular/upgrade/static';

@Directive({
  selector: 'hero-detail'
})
export class HeroDetailDirective extends UpgradeComponent {
  constructor(elementRef: ElementRef, injector: Injector) {
    super('heroDetail', elementRef, injector);
  }
}
    

      
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@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  declarations: [
    HeroDetailDirective,
/* . . . */
  ]
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.body, ['heroApp'], { strictDi: true });
  }
}
    

升级后的组件也可能有输入属性和输出属性，它们是在原 AngularJS 组件型指令的 scope/controller 绑定中定义的。 当你从 Angular 模板中使用该组件时，就要使用Angular 模板语法来提供这些输入属性和输出属性，但要遵循下列规则：

An upgraded component may also have inputs and outputs, as defined by the scope/controller bindings of the original AngularJS component directive. When you use the component from an Angular template, provide the inputs and outputs using Angular template syntax, observing the following rules:

举个例子，假设 AngularJS 中有一个表示“英雄详情”的组件型指令，它带有一个输入属性和一个输出属性：

For example, imagine a hero detail AngularJS component directive with one input and one output:

      
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export const heroDetail = {
  bindings: {
    hero: '<',
    deleted: '&'
  },
  template: `
    <h2>{{$ctrl.hero.name}} details!</h2>
    <div><label>id: </label>{{$ctrl.hero.id}}</div>
    <button ng-click="$ctrl.onDelete()">Delete</button>
  `,
  controller: function() {
    this.onDelete = () => {
      this.deleted(this.hero);
    };
  }
};
    

你可以把这个组件升级到 Angular，然后使用 Angular 的模板语法提供这个输入属性和输出属性：

You can upgrade this component to Angular, annotate inputs and outputs in the upgrade directive, and then provide the input and output using Angular template syntax:

      
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import { Directive, ElementRef, Injector, Input, Output, EventEmitter } from '@angular/core';
import { UpgradeComponent } from '@angular/upgrade/static';
import { Hero } from '../hero';
 
@Directive({
  selector: 'hero-detail'
})
export class HeroDetailDirective extends UpgradeComponent {
  @Input() hero: Hero;
  @Output() deleted: EventEmitter<Hero>;
 
  constructor(elementRef: ElementRef, injector: Injector) {
    super('heroDetail', elementRef, injector);
  }
}
    

      
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import { Component } from '@angular/core';
import { Hero } from '../hero';
 
@Component({
  selector: 'my-container',
  template: `
    <h1>Tour of Heroes</h1>
    <hero-detail [hero]="hero"
                 (deleted)="heroDeleted($event)">
    </hero-detail>
  `
})
export class ContainerComponent {
  hero = new Hero(1, 'Windstorm');
  heroDeleted(hero: Hero) {
    hero.name = 'Ex-' + hero.name;
  }
}
    

把 AngularJS 的内容投影到 Angular 组件中link

Projecting AngularJS Content into Angular Componentslink

如果你在 AngularJS 模板中使用降级后的 Angular 组件时，可能会需要把模板中的一些内容投影进那个组件。 这也是可能的，虽然在 Angular 中并没有透传(transclude)这样的东西，但它有一个非常相似的概念，叫做内容投影。 UpgradeModule 也能让这两个特性实现互操作。

When you are using a downgraded Angular component from an AngularJS template, the need may arise to transclude some content into it. This is also possible. While there is no such thing as transclusion in Angular, there is a very similar concept called content projection. upgrade/static is able to make these two features interoperate.

Angular 的组件通过使用 <ng-content> 标签来支持内容投影。下面是这类组件的一个例子：

Angular components that support content projection make use of an <ng-content> tag within them. Here's an example of such a component:

      
        content_copy
      
      
import { Component, Input } from '@angular/core';
import { Hero } from '../hero';
 
@Component({
  selector: 'hero-detail',
  template: `
    <h2>{{hero.name}}</h2>
    <div>
      <ng-content></ng-content>
    </div>
  `
})
export class HeroDetailComponent {
  @Input() hero: Hero;
}
    

当从 AngularJS 中使用该组件时，你可以为它提供内容。正如它们将在 AngularJS 中被透传一样， 它们也在 Angular 中被投影到了 <ng-content> 标签所在的位置：

When using the component from AngularJS, you can supply contents for it. Just like they would be transcluded in AngularJS, they get projected to the location of the <ng-content> tag in Angular:

      
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      <div ng-controller="MainController as mainCtrl">
  <hero-detail [hero]="mainCtrl.hero">
    <!-- Everything here will get projected -->
    <p>{{mainCtrl.hero.description}}</p>
  </hero-detail>
</div>
    

把 Angular 的内容透传进 AngularJS 的组件型指令link

Transcluding Angular Content into AngularJS Component Directiveslink

就像可以把 AngularJS 的内容投影进 Angular 组件一样，你也能把 Angular 的内容透传进 AngularJS 的组件， 但不管怎样，你都要使用它们升级过的版本。

Just as you can project AngularJS content into Angular components, you can transclude Angular content into AngularJS components, whenever you are using upgraded versions from them.

如果一个 AngularJS 组件型指令支持透传，它就会在自己的模板中使用 ng-transclude 指令标记出透传到的位置：

When an AngularJS component directive supports transclusion, it may use the ng-transclude directive in its template to mark the transclusion point:

      
        content_copy
      
      
export const heroDetail = {
  bindings: {
    hero: '='
  },
  template: `
    <h2>{{$ctrl.hero.name}}</h2>
    <div>
      <ng-transclude></ng-transclude>
    </div>
  `,
  transclude: true
};
    

如果你升级这个组件，并把它用在 Angular 中，你就能把准备透传的内容放进这个组件的标签中。

If you upgrade this component and use it from Angular, you can populate the component tag with contents that will then get transcluded:

      
        content_copy
      
      
import { Component } from '@angular/core';
import { Hero } from '../hero';
 
@Component({
  selector: 'my-container',
  template: `
    <hero-detail [hero]="hero">
      <!-- Everything here will get transcluded -->
      <p>{{hero.description}}</p>
    </hero-detail>
  `
})
export class ContainerComponent {
  hero = new Hero(1, 'Windstorm', 'Specific powers of controlling winds');
}
    

让 AngularJS 中的依赖可被注入到 Angularlink

Making AngularJS Dependencies Injectable to Angularlink

当运行一个混合式应用时，可能会遇到这种情况：你需要把某些 AngularJS 的依赖注入到 Angular 代码中。 这可能是因为某些业务逻辑仍然在 AngularJS 服务中，或者需要某些 AngularJS 的内置服务，比如 $location 或 $timeout。

When running a hybrid app, you may encounter situations where you need to inject some AngularJS dependencies into your Angular code. Maybe you have some business logic still in AngularJS services. Maybe you want access to AngularJS's built-in services like $location or $timeout.

在这些情况下，把一个 AngularJS 提供商升级到Angular 也是有可能的。这就让它将来有可能被注入到 Angular 代码中的某些地方。 比如，你可能在 AngularJS 中有一个名叫 HeroesService 的服务：

In these situations, it is possible to upgrade an AngularJS provider to Angular. This makes it possible to then inject it somewhere in Angular code. For example, you might have a service called HeroesService in AngularJS:

      
        content_copy
      
      import { Hero } from '../hero';

export class HeroesService {
  get() {
    return [
      new Hero(1, 'Windstorm'),
      new Hero(2, 'Spiderman')
    ];
  }
}
    

你可以用 Angular 的工厂提供商升级该服务， 它从 AngularJS 的 $injector 请求服务。

You can upgrade the service using a Angular factory provider that requests the service from the AngularJS $injector.

很多开发者都喜欢在一个独立的 ajs-upgraded-providers.ts 中声明这个工厂提供商，以便把它们都放在一起，这样便于引用、创建新的以及在升级完毕时删除它们。

Many developers prefer to declare the factory provider in a separate ajs-upgraded-providers.ts file so that they are all together, making it easier to reference them, create new ones and delete them once the upgrade is over.

同时，建议导出 heroesServiceFactory 函数，以便 AOT 编译器可以拿到它们。

It's also recommended to export the heroesServiceFactory function so that Ahead-of-Time compilation can pick it up.

      
        content_copy
      
      import { HeroesService } from './heroes.service';

export function heroesServiceFactory(i: any) {
  return i.get('heroes');
}

export const heroesServiceProvider = {
  provide: HeroesService,
  useFactory: heroesServiceFactory,
  deps: ['$injector']
};
    

然后，你就可以把这个服务添加到 @NgModule 中来把它暴露给 Angular：

You can then provide the service to Angular by adding it to the @NgModule:

      
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import { heroesServiceProvider } from './ajs-upgraded-providers';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  providers: [
    heroesServiceProvider
  ],
/* . . . */
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.body, ['heroApp'], { strictDi: true });
  }
}
    

然后在组件的构造函数中使用该服务的类名作为类型注解注入到组件中，从而在组件中使用它：

Then use the service inside your component by injecting it in the component constructor using its class as a type annotation:

      
        content_copy
      
      
import { Component } from '@angular/core';
import { HeroesService } from './heroes.service';
import { Hero } from '../hero';
 
@Component({
  selector: 'hero-detail',
  template: `
    <h2>{{hero.id}}: {{hero.name}}</h2>
  `
})
export class HeroDetailComponent {
  hero: Hero;
  constructor(heroes: HeroesService) {
    this.hero = heroes.get()[0];
  }
}
    

让 Angular 的依赖能被注入到 AngularJS 中link

Making Angular Dependencies Injectable to AngularJSlink

除了能升级 AngularJS 依赖之外，你还能降级Angular 的依赖，以便在 AngularJS 中使用它们。 当你已经开始把服务移植到 Angular 或在 Angular 中创建新服务，但同时还有一些用 AngularJS 写成的组件时，这会非常有用。

In addition to upgrading AngularJS dependencies, you can also downgrade Angular dependencies, so that you can use them from AngularJS. This can be useful when you start migrating services to Angular or creating new services in Angular while retaining components written in AngularJS.

例如，你可能有一个 Angular 的 Heroes 服务：

For example, you might have an Angular service called Heroes:

      
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import { Injectable } from '@angular/core';
import { Hero } from '../hero';
 
@Injectable()
export class Heroes {
  get() {
    return [
      new Hero(1, 'Windstorm'),
      new Hero(2, 'Spiderman')
    ];
  }
}
    

仿照 Angular 组件，把该提供商加入 NgModule 的 providers 列表中，以注册它。

Again, as with Angular components, register the provider with the NgModule by adding it to the module's providers list.

      
        content_copy
      
      
import { Heroes } from './heroes';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule
  ],
  providers: [ Heroes ]
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.body, ['heroApp'], { strictDi: true });
  }
}
    

现在，用 upgradeAdapter.downgradeNg2Provider() 来把 Angular 的 Heroes 包装成AngularJS 的工厂函数，并把这个工厂注册进 AngularJS 的模块中。 依赖在 AngularJS 中的名字你可以自己定：

Now wrap the Angular Heroes in an AngularJS factory function using downgradeInjectable() and plug the factory into an AngularJS module. The name of the AngularJS dependency is up to you:

      
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      import { Heroes } from './heroes';
/* . . . */
import { downgradeInjectable } from '@angular/upgrade/static';

angular.module('heroApp', [])
  .factory('heroes', downgradeInjectable(Heroes))
  .component('heroDetail', heroDetailComponent);
    

此后，该服务就能被注入到 AngularJS 代码中的任何地方了：

After this, the service is injectable anywhere in AngularJS code:

      
        content_copy
      
      export const heroDetailComponent = {
  template: `
    <h2>{{$ctrl.hero.id}}: {{$ctrl.hero.name}}</h2>
  `,
  controller: ['heroes', function(heroes: Heroes) {
    this.hero = heroes.get()[0];
  }]
};
    

在混合式应用中使用 AOT 编译link

Using Ahead-of-time compilation with hybrid appslink

你也可以其它 Angular 应用一样在混合式应用中发挥 AOT 编译的优势。 对混合式应用的设置过程和预编译章节中所讲的几乎完全一样，不同点在于 index.html 和 main-aot.ts 中。

You can take advantage of Ahead-of-time (AOT) compilation on hybrid apps just like on any other Angular application. The setup for an hybrid app is mostly the same as described in the Ahead-of-time Compilation chapter save for differences in index.html and main-aot.ts

index.html 仍然需要 script 标签来加载 AngularJS 的文件，因此供 AOT 编译的 index.html 也需要加载那些文件。 复制它们的简单方案是把它们全都添加到 copy-dist-files.js 文件中。

The index.html will likely have script tags loading AngularJS files, so the index.html for AOT must also load those files. An easy way to copy them is by adding each to the copy-dist-files.js file.

你还要使用所生成的 AppModuleFactory 而不是原来的 AppModule 来引导一个混合式应用：

You'll need to use the generated AppModuleFactory, instead of the original AppModule to bootstrap the hybrid app:

      
        content_copy
      
      import { platformBrowser } from '@angular/platform-browser';

import { AppModuleNgFactory } from './app.module.ngfactory';

platformBrowser().bootstrapModuleFactory(AppModuleNgFactory);
    

这就是你为获取 Angular 应用的 AOT 优势所要做的一切。

And that's all you need do to get the full benefit of AOT for Angular apps!

PhoneCat 升级教程link

PhoneCat Upgrade Tutoriallink

在本节和下节中，你将看一个完整的例子，它使用 upgrade 模块准备和升级了一个应用程序。 该应用就是来自原 AngularJS 教程中的Angular PhoneCat。 那是我们很多人当初开始 Angular 探险之旅的地方。 现在，你会看到如何把该应用带入 Angular 的美丽新世界。

In this section, you'll learn to prepare and upgrade an application with ngUpgrade. The example app is Angular PhoneCat from the original AngularJS tutorial, which is where many of us began our Angular adventures. Now you'll see how to bring that application to the brave new world of Angular.

这期间，你将学到如何在实践中应用准备指南中列出的那些重点步骤： 你先让该应用向 Angular 看齐，然后为它引入 SystemJS 模块加载器和 TypeScript。

During the process you'll learn how to apply the steps outlined in the preparation guide. You'll align the application with Angular and also start writing in TypeScript.

要跟随本教程，请先把angular-phonecat仓库克隆到本地，并应用这些步骤。

To follow along with the tutorial, clone the angular-phonecat repository and apply the steps as you go.

在项目结构方面，工作的起点是这样的：

In terms of project structure, this is where the work begins:

这确实是一个很好地起点。这些代码使用了 AngularJS 1.5 的组件 API，并遵循了 AngularJS 风格指南进行组织， 在成功升级之前，这是一个很重要的准备步骤。

This is actually a pretty good starting point. The code uses the AngularJS 1.5 component API and the organization follows the AngularJS Style Guide, which is an important preparation step before a successful upgrade.

• 每个组件、服务和过滤器都在它自己的源文件中 —— 就像单一规则所要求的。

  Each component, service, and filter is in its own source file, as per the Rule of 1.

• core、phone-detail 和 phone-list 模块都在它们自己的子目录中。那些子目录除了包含 HTML 模板之外，还包含 JavaScript 代码，它们共同完成一个特性。 这是按特性分目录的结构 和模块化规则所要求的。

  The core, phone-detail, and phone-list modules are each in their own subdirectory. Those subdirectories contain the JavaScript code as well as the HTML templates that go with each particular feature. This is in line with the Folders-by-Feature Structure and Modularity rules.

• 单元测试都和应用代码在一起，它们很容易找到。就像规则 组织测试文件中要求的那样。

  Unit tests are located side-by-side with application code where they are easily found, as described in the rules for Organizing Tests.

切换到 TypeScriptlink

Switching to TypeScriptlink

因为你将使用 TypeScript 编写 Angular 的代码，所以在开始升级之前，先要把 TypeScript 的编译器设置好。

Since you're going to be writing Angular code in TypeScript, it makes sense to bring in the TypeScript compiler even before you begin upgrading.

你还将开始逐步淘汰 Bower 包管理器，换成 NPM。后面你将使用 NPM 来安装新的依赖包，并最终从项目中移除 Bower。

You'll also start to gradually phase out the Bower package manager in favor of NPM, installing all new dependencies using NPM, and eventually removing Bower from the project.

先把 TypeScript 包安装到项目中。

Begin by installing TypeScript to the project.

      
        content_copy
      
      npm i typescript --save-dev
    

还要为那些没有自带类型信息的库（比如 AngularJS 和 Jasmine）安装类型定义文件。

Install type definitions for the existing libraries that you're using but that don't come with prepackaged types: AngularJS and the Jasmine unit test framework.

      
        content_copy
      
      npm install @types/jasmine @types/angular @types/angular-animate @types/angular-cookies @types/angular-mocks @types/angular-resource @types/angular-route @types/angular-sanitize --save-dev
    

你还应该要往项目目录下添加一个 tsconfig.json 文件， 就像在 TypeScript 配置中讲过的那样。 tsconfig.json 文件会告诉 TypeScript 编译器如何把 TypeScript 文件转成 ES5 代码，并打包进 CommonJS 模块中。

You should also configure the TypeScript compiler with a tsconfig.json in the project directory as described in the TypeScript Configuration guide. The tsconfig.json file tells the TypeScript compiler how to turn your TypeScript files into ES5 code bundled into CommonJS modules.

最后，你应该把下列 npm 脚本添加到 package.json 中，用于把 TypeScript 文件编译成 JavaScript （根据 tsconfig.json 的配置）：

Finally, you should add some npm scripts in package.json to compile the TypeScript files to JavaScript (based on the tsconfig.json configuration file):

      
        content_copy
      
      "script": {
  "tsc": "tsc",
  "tsc:w": "tsc -w",
  ...
    

现在，从命令行中用监视模式启动 TypeScript 编译器：

Now launch the TypeScript compiler from the command line in watch mode:

      
        content_copy
      
      npm run tsc:w
    

让这个进程一直在后台运行，监听任何变化并自动重新编译。

Keep this process running in the background, watching and recompiling as you make changes.

接下来，把 JavaScript 文件转换成 TypeScript 文件。 由于 TypeScript 是 ECMAScript 2015 的一个超集，而 ES2015 又是 ECMAScript 5 的超集，所以你可以简单的把文件的扩展名从 .js 换成 .ts， 它们还是会像以前一样工作。由于 TypeScript 编译器仍在运行，它会为每一个 .ts 文件生成对应的 .js 文件，而真正运行的是编译后的 .js 文件。 如果你用 npm start 开启了本项目的 HTTP 服务器，你会在浏览器中看到一个功能完好的应用。

Next, convert your current JavaScript files into TypeScript. Since TypeScript is a super-set of ECMAScript 2015, which in turn is a super-set of ECMAScript 5, you can simply switch the file extensions from .js to .ts and everything will work just like it did before. As the TypeScript compiler runs, it emits the corresponding .js file for every .ts file and the compiled JavaScript is what actually gets executed. If you start the project HTTP server with npm start, you should see the fully functional application in your browser.

有了 TypeScript，你就可以从它的一些特性中获益了。此语言可以为 AngularJS 应用提供很多价值。

Now that you have TypeScript though, you can start benefiting from some of its features. There's a lot of value the language can provide to AngularJS applications.

首先，TypeScript 是一个 ES2015 的超集。任何以前用 ES5 写的程序(就像 PhoneCat 范例)都可以开始通过 TypeScript 纳入那些添加到 ES2015 中的新特性。 这包括 let、const、箭头函数、函数默认参数以及解构(destructure)赋值。

For one thing, TypeScript is a superset of ES2015. Any app that has previously been written in ES5 - like the PhoneCat example has - can with TypeScript start incorporating all of the JavaScript features that are new to ES2015. These include things like lets and consts, arrow functions, default function parameters, and destructuring assignments.

你能做的另一件事就是把类型安全添加到代码中。这实际上已经部分完成了，因为你已经安装了 AngularJS 的类型定义。 TypeScript 会帮你检查是否正确调用了 AngularJS 的 API，—— 比如往 Angular 模块中注册组件。

Another thing you can do is start adding type safety to your code. This has actually partially already happened because of the AngularJS typings you installed. TypeScript are checking that you are calling AngularJS APIs correctly when you do things like register components to Angular modules.

你还能开始把类型注解添加到自己的代码中，来从 TypeScript 的类型系统中获得更多帮助。 比如，你可以给 checkmark 过滤器加上注解，表明它期待一个 boolean 类型的参数。 这可以更清楚的表明此过滤器打算做什么

But you can also start adding type annotations to get even more out of TypeScript's type system. For instance, you can annotate the checkmark filter so that it explicitly expects booleans as arguments. This makes it clearer what the filter is supposed to do.

      
        content_copy
      
      angular.
  module('core').
  filter('checkmark', function() {
    return function(input: boolean) {
      return input ? '\u2713' : '\u2718';
    };
  });
    

在 Phone 服务中，你可以明确的把 $resource 服务声明为 angular.resource.IResourceService，一个 AngularJS 类型定义提供的类型。

In the Phone service, you can explicitly annotate the $resource service dependency as an angular.resource.IResourceService - a type defined by the AngularJS typings.

      
        content_copy
      
      
angular.
  module('core.phone').
  factory('Phone', ['$resource',
    function($resource: angular.resource.IResourceService) {
      return $resource('phones/:phoneId.json', {}, {
        query: {
          method: 'GET',
          params: {phoneId: 'phones'},
          isArray: true
        }
      });
    }
  ]);
    

你可以在应用的路由配置中使用同样的技巧，那里你用到了 location 和 route 服务。 一旦为它们提供了类型信息，TypeScript 就能检查你是否在用类型的正确参数来调用它们了。

You can apply the same trick to the application's route configuration file in app.config.ts, where you are using the location and route services. By annotating them accordingly TypeScript can verify you're calling their APIs with the correct kinds of arguments.

      
        content_copy
      
      
angular.
  module('phonecatApp').
  config(['$locationProvider', '$routeProvider',
    function config($locationProvider: angular.ILocationProvider,
                    $routeProvider: angular.route.IRouteProvider) {
      $locationProvider.hashPrefix('!');
 
      $routeProvider.
        when('/phones', {
          template: '<phone-list></phone-list>'
        }).
        when('/phones/:phoneId', {
          template: '<phone-detail></phone-detail>'
        }).
        otherwise('/phones');
    }
  ]);
    

你能用的另一个 TypeScript 特性是类。具体来讲，你可以把控制器转换成类。 这种方式下，你离成为 Angular 组件类就又近了一步，它会令你的升级之路变得更简单。

Another TypeScript feature you can make use of is classes. In particular, you can turn component controllers into classes. That way they'll be a step closer to becoming Angular component classes, which will make life easier once you upgrade.

AngularJS 期望控制器是一个构造函数。这实际上就是 ES2015/TypeScript 中的类， 这也就意味着只要你把一个类注册为组件控制器，AngularJS 就会愉快的使用它。

AngularJS expects controllers to be constructor functions. That's exactly what ES2015/TypeScript classes are under the hood, so that means you can just plug in a class as a component controller and AngularJS will happily use it.

新的“电话列表(phone list)”组件控制器类是这样的：

Here's what the new class for the phone list component controller looks like:

      
        content_copy
      
      
class PhoneListController {
  phones: any[];
  orderProp: string;
  query: string;
 
  static $inject = ['Phone'];
  constructor(Phone: any) {
    this.phones = Phone.query();
    this.orderProp = 'age';
  }
 
}
 
angular.
  module('phoneList').
  component('phoneList', {
    templateUrl: 'phone-list/phone-list.template.html',
    controller: PhoneListController
  });
    

以前在控制器函数中实现的一切，现在都改由类的构造函数来实现了。类型注入注解通过静态属性 $inject 被附加到了类上。在运行时，它们变成了 PhoneListController.$inject。

What was previously done in the controller function is now done in the class constructor function. The dependency injection annotations are attached to the class using a static property $inject. At runtime this becomes the PhoneListController.$inject property.

该类还声明了另外三个成员：电话列表、当前排序键的名字和搜索条件。 这些东西你以前就加到了控制器上，只是从来没有在任何地方显式定义过它们。最后一个成员从未真正在 TypeScript 代码中用过， 因为它只是在模板中被引用过。但为了清晰起见，你还是应该定义出此控制器应有的所有成员。

The class additionally declares three members: The array of phones, the name of the current sort key, and the search query. These are all things you have already been attaching to the controller but that weren't explicitly declared anywhere. The last one of these isn't actually used in the TypeScript code since it's only referred to in the template, but for the sake of clarity you should define all of the controller members.

在电话详情控制器中，你有两个成员：一个是用户正在查看的电话，另一个是正在显示的图像：

In the Phone detail controller, you'll have two members: One for the phone that the user is looking at and another for the URL of the currently displayed image:

      
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class PhoneDetailController {
  phone: any;
  mainImageUrl: string;
 
  static $inject = ['$routeParams', 'Phone'];
  constructor($routeParams: angular.route.IRouteParamsService, Phone: any) {
    let phoneId = $routeParams['phoneId'];
    this.phone = Phone.get({phoneId}, (phone: any) => {
      this.setImage(phone.images[0]);
    });
  }
 
  setImage(imageUrl: string) {
    this.mainImageUrl = imageUrl;
  }
}
 
angular.
  module('phoneDetail').
  component('phoneDetail', {
    templateUrl: 'phone-detail/phone-detail.template.html',
    controller: PhoneDetailController
  });
    

这已经让你的控制器代码看起来更像 Angular 了。你的准备工作做好了，可以引进 Angular 到项目中了。

This makes the controller code look a lot more like Angular already. You're all set to actually introduce Angular into the project.

如果项目中有任何 AngularJS 的服务，它们也是转换成类的优秀候选人，像控制器一样，它们也是构造函数。 但是在本项目中，你只有一个 Phone 工厂，这有点特别，因为它是一个 ngResource 工厂。 所以你不会在准备阶段中处理它，而是在下一节中直接把它转换成 Angular 服务。

If you had any AngularJS services in the project, those would also be a good candidate for converting to classes, since like controllers, they're also constructor functions. But you only have the Phone factory in this project, and that's a bit special since it's an ngResource factory. So you won't be doing anything to it in the preparation stage. You'll instead turn it directly into an Angular service.

安装 Angularlink

Installing Angularlink

准备工作做完了，接下来就开始把 PhoneCat 升级到 Angular。 你将在 Angular升级模块的帮助下增量式的完成此项工作。 做完这些之后，就能把 AngularJS 从项目中完全移除了，但其中的关键是在不破坏此程序的前提下一小块一小块的完成它。

Having completed the preparation work, get going with the Angular upgrade of PhoneCat. You'll do this incrementally with the help of ngUpgrade that comes with Angular. By the time you're done, you'll be able to remove AngularJS from the project completely, but the key is to do this piece by piece without breaking the application.

用 SystemJS 模块加载器把 Angular 安装到项目中。 看看搭建本地开发环境中的指南，并从那里获得如下配置：

Install Angular into the project, along with the SystemJS module loader. Take a look at the results of the Setup instructions and get the following configurations from there:

• 把 Angular 和其它新依赖添加到 package.json 中

  Add Angular and the other new dependencies to package.json

• 把 SystemJS 的配置文件 systemjs.config.js 添加到项目的根目录。

  The SystemJS configuration file systemjs.config.js to the project root directory.

这些完成之后，就运行：

Once these are done, run:

      
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      npm install
    

很快你就可以通过 index.html 来把 Angular 的依赖快速加载到应用中， 但首先，你得做一些目录结构调整。这是因为你正准备从 node_modules 中加载文件，然而目前项目中的每一个文件都是从 /app 目录下加载的。

Soon you can load Angular dependencies into the application via index.html, but first you need to do some directory path adjustments. You'll need to load files from node_modules and the project root instead of from the /app directory as you've been doing to this point.

把 app/index.html 移入项目的根目录，然后把 package.json 中的开发服务器根目录也指向项目的根目录，而不再是 app 目录：

Move the app/index.html file to the project root directory. Then change the development server root path in package.json to also point to the project root instead of app:

      
        content_copy
      
      "start": "http-server ./ -a localhost -p 8000 -c-1",
    

现在，你就能把项目根目录下的每一样东西发给浏览器了。但你不想为了适应开发环境中的设置，被迫修改应用代码中用到的所有图片和数据的路径。因此，你要往 index.html 中添加一个 <base> 标签，它将导致各种相对路径被解析回 /app 目录：

Now you're able to serve everything from the project root to the web browser. But you do not want to have to change all the image and data paths used in the application code to match the development setup. For that reason, you'll add a <base> tag to index.html, which will cause relative URLs to be resolved back to the /app directory:

      
        content_copy
      
      <base href="/app/">
    

现在你可以通过 SystemJS 加载 Angular 了。你还要把 Angular 的腻子脚本(polyfills) 和 SystemJS 的配置加到 <head> 区的末尾，然后，你能就用 System.import 来加载实际的应用了：

Now you can load Angular via SystemJS. You'll add the Angular polyfills and the SystemJS config to the end of the <head> section, and then you'll use System.import to load the actual application:

      
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      <script src="/node_modules/core-js/client/shim.min.js"></script>
<script src="/node_modules/zone.js/dist/zone.js"></script>
<script src="/node_modules/systemjs/dist/system.src.js"></script>
<script src="/systemjs.config.js"></script>
<script>
  System.import('/app');
</script>
    

你还需要对搭建环境期间安装的 systemjs.config.js 文件做一些调整。

You also need to make a couple of adjustments to the systemjs.config.js file installed during setup.

在 SystemJS 加载期间为浏览器指出项目的根在哪里，而不再使用 <base> URL。

Point the browser to the project root when loading things through SystemJS, instead of using the <base> URL.

再通过 npm install @angular/upgrade --save 安装 upgrade 包，并为 @angular/upgrade/static 包添加一个映射。

Install the upgrade package via npm install @angular/upgrade --save and add a mapping for the @angular/upgrade/static package.

      
        content_copy
      
      
System.config({
    paths: {
      // paths serve as alias
      'npm:': '/node_modules/'
    },
    map: {
      'ng-loader': '../src/systemjs-angular-loader.js',
      app: '/app',
/* . . . */
      '@angular/upgrade/static': 'npm:@angular/upgrade/bundles/upgrade-static.umd.js',
/* . . . */
    },
    

创建 AppModulelink

Creating the AppModulelink

现在，创建一个名叫 AppModule 的根 NgModule 类。 这里已经有了一个名叫 app.module.ts 的文件，其中存放着 AngularJS 的模块。 把它改名为 app.module.ng1.ts，同时也要在 index.html 中修改对应的脚本名。 文件的内容保留：

Now create the root NgModule class called AppModule. There is already a file named app.module.ts that holds the AngularJS module. Rename it to app.module.ajs.ts and update the corresponding script name in the index.html as well. The file contents remain:

      
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      'use strict';

// Define the `phonecatApp` AngularJS module
angular.module('phonecatApp', [
  'ngAnimate',
  'ngRoute',
  'core',
  'phoneDetail',
  'phoneList',
]);
    

然后创建一个新的 app.module.ts 文件，其中是一个最小化的 NgModule 类：

Now create a new app.module.ts with the minimum NgModule class:

      
        content_copy
      
      import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';

@NgModule({
  imports: [
    BrowserModule,
  ],
})
export class AppModule {
}
    

引导 PhoneCat 的混合式应用link

Bootstrapping a hybrid PhoneCatlink

接下来，你把该应用程序引导改装为一个同时支持 AngularJS 和 Angular 的混合式应用。 然后，就能开始把这些不可分割的小块转换到 Angular 了。

Next, you'll bootstrap the application as a hybrid application that supports both AngularJS and Angular components. After that, you can start converting the individual pieces to Angular.

本应用现在是使用宿主页面中附加到 <html> 元素上的 AngularJS 指令 ng-app 引导的。 但在混合式应用中，不能再这么用了。你得用ngUpgrade bootstrap方法代替。

The application is currently bootstrapped using the AngularJS ng-app directive attached to the <html> element of the host page. This will no longer work in the hybrid app. Switch to the ngUpgrade bootstrap method instead.

首先，从 index.html 中移除 ng-app。然后在 AppModule 中导入 UpgradeModule，并改写它的 ngDoBootstrap 方法：

First, remove the ng-app attribute from index.html. Then import UpgradeModule in the AppModule, and override its ngDoBootstrap method:

      
        content_copy
      
      
import { UpgradeModule } from '@angular/upgrade/static';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
  ],
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.documentElement, ['phonecatApp']);
  }
}
    

注意，你正在从内部的 ngDoBootstrap 中引导 AngularJS 模块。 它的参数和你在手动引导 AngularJS 时传给 angular.bootstrap 的是一样的：应用的根元素，和所要加载的 AngularJS 1.x 模块的数组。

Note that you are bootstrapping the AngularJS module from inside ngDoBootstrap. The arguments are the same as you would pass to angular.bootstrap if you were manually bootstrapping AngularJS: the root element of the application; and an array of the AngularJS 1.x modules that you want to load.

最后，在 app/main.ts 中引导这个 AppModule。该文件在 systemjs.config.js 中被配置为了应用的入口，所以它已经被加载进了浏览器中。

Finally, bootstrap the AppModule in app/main.ts. This file has been configured as the application entrypoint in systemjs.config.js, so it is already being loaded by the browser.

      
        content_copy
      
      import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { AppModule } from './app.module';

platformBrowserDynamic().bootstrapModule(AppModule);
    

现在，你同时运行着 AngularJS 和 Angular。漂亮！不过你还没有运行什么实际的 Angular 组件，这就是接下来要做的。

Now you're running both AngularJS and Angular at the same time. That's pretty exciting! You're not running any actual Angular components yet. That's next.

升级 Phone 服务link

Upgrading the Phone servicelink

你要移植到 Angular 的第一个片段是 Phone 工厂(位于 app/js/core/phones.factory.ts)， 并且让它能帮助控制器从服务器上加载电话信息。目前，它是用 ngResource 实现的，你用它做两件事：

The first piece you'll port over to Angular is the Phone service, which resides in app/core/phone/phone.service.ts and makes it possible for components to load phone information from the server. Right now it's implemented with ngResource and you're using it for two things:

• 把所有电话的列表加载到电话列表组件中。

  For loading the list of all phones into the phone list component.

• 把一台电话的详情加载到电话详情组件中。

  For loading the details of a single phone into the phone detail component.

你可以用 Angular 的服务类来替换这个实现，而把控制器继续留在 AngularJS 的地盘上。

You can replace this implementation with an Angular service class, while keeping the controllers in AngularJS land.

在这个新版本中，你导入了 Angular 的 HTTP 模块，并且用它的 Http 服务替换掉 NgResource。

In the new version, you import the Angular HTTP module and call its Http service instead of ngResource.

再次打开 app.module.ts 文件，导入并把 HttpModule 添加到 AppModule 的 imports 数组中：

Re-open the app.module.ts file, import and add HttpModule to the imports array of the AppModule:

      
        content_copy
      
      
import { HttpModule } from '@angular/http';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
    HttpModule,
  ],
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.documentElement, ['phonecatApp']);
  }
}
    

现在，你已经准备好了升级 Phones 服务本身。你将为 phone.service.ts 文件中基于 ngResource 的服务加上 @Injectable 装饰器：

Now you're ready to upgrade the Phone service itself. Replace the ngResource-based service in phone.service.ts with a TypeScript class decorated as @Injectable:

      
        content_copy
      
      @Injectable()
export class Phone {
/* . . . */
}
    

@Injectable 装饰器将把一些依赖注入相关的元数据附加到该类上，让 Angular 知道它的依赖信息。 就像在依赖注入指南中描述过的那样， 这是一个标记装饰器，你要把它用在那些没有其它 Angular 装饰器，并且自己有依赖注入的类上。

The @Injectable decorator will attach some dependency injection metadata to the class, letting Angular know about its dependencies. As described by the Dependency Injection Guide, this is a marker decorator you need to use for classes that have no other Angular decorators but still need to have their dependencies injected.

在它的构造函数中，该类期待一个 Http 服务。Http 服务将被注入进来并存入一个私有字段。 然后该服务在两个实例方法中被使用到，一个加载所有电话的列表，另一个加载一台指定电话的详情：

In its constructor the class expects to get the Http service. It will be injected to it and it is stored as a private field. The service is then used in the two instance methods, one of which loads the list of all phones, and the other loads the details of a specified phone:

      
        content_copy
      
      
@Injectable()
export class Phone {
  constructor(private http: Http) { }
  query(): Observable<PhoneData[]> {
    return this.http.get(`phones/phones.json`).pipe(
      map((res: Response) => res.json())
    );
  }
  get(id: string): Observable<PhoneData> {
    return this.http.get(`phones/${id}.json`).pipe(
      map((res: Response) => res.json())
    );
  }
}
    

该方法现在返回一个 Phone 类型或 Phone[] 类型的可观察对象(Observable)。 这是一个你从未用过的类型，因此你得为它新增一个简单的接口：

The methods now return observables of type PhoneData and PhoneData[]. This is a type you don't have yet. Add a simple interface for it:

      
        content_copy
      
      export interface PhoneData {
  name: string;
  snippet: string;
  images: string[];
}
    

@angular/upgrade/static 有一个 downgradeInjectable 方法，可以使 Angular 服务在 AngularJS 的代码中可用。 使用它来插入 Phone 服务：

@angular/upgrade/static has a downgradeInjectable method for the purpose of making Angular services available to AngularJS code. Use it to plug in the Phone service:

      
        content_copy
      
      declare var angular: angular.IAngularStatic;
import { downgradeInjectable } from '@angular/upgrade/static';
/* . . . */
@Injectable()
export class Phone {
/* . . . */
}

angular.module('core.phone')
  .factory('phone', downgradeInjectable(Phone));
    

最终，该类的全部代码如下：

Here's the full, final code for the service:

      
        content_copy
      
      
import { Injectable } from '@angular/core';
import { Http, Response } from '@angular/http';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';
 
declare var angular: angular.IAngularStatic;
import { downgradeInjectable } from '@angular/upgrade/static';
 
export interface PhoneData {
  name: string;
  snippet: string;
  images: string[];
}
 
@Injectable()
export class Phone {
  constructor(private http: Http) { }
  query(): Observable<PhoneData[]> {
    return this.http.get(`phones/phones.json`).pipe(
      map((res: Response) => res.json())
    );
  }
  get(id: string): Observable<PhoneData> {
    return this.http.get(`phones/${id}.json`).pipe(
      map((res: Response) => res.json())
    );
  }
}
 
angular.module('core.phone')
  .factory('phone', downgradeInjectable(Phone));
    

注意，你要单独导入了 RxJS Observable 中的 map 操作符。 对每个 RxJS 操作符都要这么做。

Notice that you're importing the map operator of the RxJS Observable separately. Do this for every RxJS operator.

这个新的 Phone 服务具有和老的基于 ngResource 的服务相同的特性。 因为它是 Angular 服务，你通过 NgModule 的 providers 数组来注册它：

The new Phone service has the same features as the original, ngResource-based service. Because it's an Angular service, you register it with the NgModule providers:

      
        content_copy
      
      
import { Phone } from './core/phone/phone.service';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
    HttpModule,
  ],
  providers: [
    Phone,
  ]
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.documentElement, ['phonecatApp']);
  }
}
    

现在，你正在用 SystemJS 加载 phone.service.ts，你应该从 index.html 中移除该服务的 <script> 标签。 这也是你在升级所有组件时将会做的事。在从 AngularJS 向 Angular 升级的同时，你也把代码从脚本移植为模块。

Now that you are loading phone.service.ts through an import that is resolved by SystemJS, you should remove the <script> tag for the service from index.html. This is something you'll do to all components as you upgrade them. Simultaneously with the AngularJS to Angular upgrade you're also migrating code from scripts to modules.

这时，你可以把两个控制器从使用老的服务切换成使用新的。你像降级过的 phones 工厂一样 $inject 它， 但它实际上是一个 Phones 类的实例，并且你可以据此注解它的类型：

At this point, you can switch the two components to use the new service instead of the old one. While you $inject it as the downgraded phone factory, it's really an instance of the Phone class and you annotate its type accordingly:

      
        content_copy
      
      
declare var angular: angular.IAngularStatic;
import { Phone, PhoneData } from '../core/phone/phone.service';
 
class PhoneListController {
  phones: PhoneData[];
  orderProp: string;
 
  static $inject = ['phone'];
  constructor(phone: Phone) {
    phone.query().subscribe(phones => {
      this.phones = phones;
    });
    this.orderProp = 'age';
  }
 
}
 
angular.
  module('phoneList').
  component('phoneList', {
    templateUrl: 'app/phone-list/phone-list.template.html',
    controller: PhoneListController
  });
    

      
        content_copy
      
      
declare var angular: angular.IAngularStatic;
import { Phone, PhoneData } from '../core/phone/phone.service';
 
class PhoneDetailController {
  phone: PhoneData;
  mainImageUrl: string;
 
  static $inject = ['$routeParams', 'phone'];
  constructor($routeParams: angular.route.IRouteParamsService, phone: Phone) {
    let phoneId = $routeParams['phoneId'];
    phone.get(phoneId).subscribe(data => {
      this.phone = data;
      this.setImage(data.images[0]);
    });
  }
 
  setImage(imageUrl: string) {
    this.mainImageUrl = imageUrl;
  }
}
 
angular.
  module('phoneDetail').
  component('phoneDetail', {
    templateUrl: 'phone-detail/phone-detail.template.html',
    controller: PhoneDetailController
  });
    

这里的两个 AngularJS 控制器在使用 Angular 的服务！控制器不需要关心这一点，尽管实际上该服务返回的是可观察对象(Observable)，而不是承诺(Promise)。 无论如何，你达到的效果都是把服务移植到 Angular，而不用被迫移植组件来使用它。

Now there are two AngularJS components using an Angular service! The components don't need to be aware of this, though the fact that the service returns observables and not promises is a bit of a giveaway. In any case, what you've achieved is a migration of a service to Angular without having to yet migrate the components that use it.

升级组件link

Upgrading Componentslink

接下来，把 AngularJS 的控制器升级成 Angular 的组件。每次升级一个，同时仍然保持应用运行在混合模式下。 在做转换的同时，你还将自定义首个 Angular管道。

Upgrade the AngularJS components to Angular components next. Do it one component at a time while still keeping the application in hybrid mode. As you make these conversions, you'll also define your first Angular pipes.

先看看电话列表组件。它目前包含一个 TypeScript 控制器类和一个组件定义对象。重命名控制器类， 并把 AngularJS 的组件定义对象更换为 Angular @Component 装饰器，这样你就把它变形为 Angular 的组件了。然后，你还要从类中移除静态 $inject 属性。

Look at the phone list component first. Right now it contains a TypeScript controller class and a component definition object. You can morph this into an Angular component by just renaming the controller class and turning the AngularJS component definition object into an Angular @Component decorator. You can then also remove the static $inject property from the class:

      
        content_copy
      
      
import { Component } from '@angular/core';
import { Phone, PhoneData } from '../core/phone/phone.service';
 
@Component({
  selector: 'phone-list',
  templateUrl: './phone-list.template.html'
})
export class PhoneListComponent {
  phones: PhoneData[];
  query: string;
  orderProp: string;
 
  constructor(phone: Phone) {
    phone.query().subscribe(phones => {
      this.phones = phones;
    });
    this.orderProp = 'age';
  }
/* . . . */
}
    

selector 属性是一个 CSS 选择器，用来定义组件应该被放在页面的哪。在 AngularJS 中，你会基于组件名字来匹配， 但是在 Angular 中，你要显式指定这些选择器。本组件将会对应元素名字 phone-list，和 AngularJS 版本一样。

The selector attribute is a CSS selector that defines where on the page the component should go. In AngularJS you do matching based on component names, but in Angular you have these explicit selectors. This one will match elements with the name phone-list, just like the AngularJS version did.

现在，将组件的模版也转换为 Angular 语法。在搜索控件中，把 AngularJS 的 $ctrl 表达式替换成 Angular 的双向绑定语法 [(ngModel)]：

Now convert the template of this component into Angular syntax. The search controls replace the AngularJS $ctrl expressions with Angular's two-way [(ngModel)] binding syntax:

      
        content_copy
      
      <p>
  Search:
  <input [(ngModel)]="query" />
</p>

<p>
  Sort by:
  <select [(ngModel)]="orderProp">
    <option value="name">Alphabetical</option>
    <option value="age">Newest</option>
  </select>
</p>
    

把列表中的 ng-repeat 替换为 *ngFor 以及它的 let var of iterable 语法， 该语法在模板语法指南中讲过。 再把 img 标签的 ng-src 替换为一个标准的 src 属性(property)绑定。

Replace the list's ng-repeat with an *ngFor as described in the Template Syntax page. Replace the image tag's ng-src with a binding to the native src property.

      
        content_copy
      
      <ul class="phones">
  <li *ngFor="let phone of getPhones()"
      class="thumbnail phone-list-item">
    <a href="/#!/phones/{{phone.id}}" class="thumb">
      <img [src]="phone.imageUrl" [alt]="phone.name" />
    </a>
    <a href="/#!/phones/{{phone.id}}" class="name">{{phone.name}}</a>
    <p>{{phone.snippet}}</p>
  </li>
</ul>
    

Angular 中没有 filter 或 orderBy 过滤器link

No Angular filter or orderBy filterslink

Angular 中并不存在 AngularJS 中内置的 filter 和 orderBy 过滤器。 所以你得自己实现进行过滤和排序。

The built-in AngularJS filter and orderBy filters do not exist in Angular, so you need to do the filtering and sorting yourself.

你把 filter 和 orderBy 过滤器改成绑定到控制器中的 getPhones() 方法，通过该方法，组件本身实现了过滤和排序逻辑。

You replaced the filter and orderBy filters with bindings to the getPhones() controller method, which implements the filtering and ordering logic inside the component itself.

      
        content_copy
      
      
getPhones(): PhoneData[] {
  return this.sortPhones(this.filterPhones(this.phones));
}
 
private filterPhones(phones: PhoneData[]) {
  if (phones && this.query) {
    return phones.filter(phone => {
      let name = phone.name.toLowerCase();
      let snippet = phone.snippet.toLowerCase();
      return name.indexOf(this.query) >= 0 || snippet.indexOf(this.query) >= 0;
    });
  }
  return phones;
}
 
private sortPhones(phones: PhoneData[]) {
  if (phones && this.orderProp) {
    return phones
      .slice(0) // Make a copy
      .sort((a, b) => {
        if (a[this.orderProp] < b[this.orderProp]) {
          return -1;
        } else if ([b[this.orderProp] < a[this.orderProp]]) {
          return 1;
        } else {
          return 0;
        }
      });
  }
  return phones;
}
    

现在你需要降级你的 Angular 组件，这样你就可以在 AngularJS 中使用它了。 你要注册一个 phoneList指令，而不是注册一个组件，它是一个降级版的 Angular 组件。

Now you need to downgrade the Angular component so you can use it in AngularJS. Instead of registering a component, you register a phoneList directive, a downgraded version of the Angular component.

强制类型转换 as angular.IDirectiveFactory 告诉 TypeScript 编译器 downgradeComponent 方法 的返回值是一个指令工厂。

The as angular.IDirectiveFactory cast tells the TypeScript compiler that the return value of the downgradeComponent method is a directive factory.

      
        content_copy
      
      
declare var angular: angular.IAngularStatic;
import { downgradeComponent } from '@angular/upgrade/static';
 
/* . . . */
@Component({
  selector: 'phone-list',
  templateUrl: './phone-list.template.html'
})
export class PhoneListComponent {
/* . . . */
}
 
angular.module('phoneList')
  .directive(
    'phoneList',
    downgradeComponent({component: PhoneListComponent}) as angular.IDirectiveFactory
  );
    

新的 PhoneListComponent 使用 Angular 的 ngModel 指令，它位于 FormsModule 中。 把 FormsModule 添加到 NgModule 的 imports 中，并声明新的 PhoneListComponent 组件， 最后，把降级的结果添加到 entryComponents中：

The new PhoneListComponent uses the Angular ngModel directive, located in the FormsModule. Add the FormsModule to NgModule imports, declare the new PhoneListComponent and finally add it to entryComponents since you downgraded it:

      
        content_copy
      
      
import { FormsModule } from '@angular/forms';
import { PhoneListComponent } from './phone-list/phone-list.component';
 
@NgModule({
  imports: [
    BrowserModule,
    UpgradeModule,
    HttpModule,
    FormsModule,
  ],
  declarations: [
    PhoneListComponent,
  ],
  entryComponents: [
    PhoneListComponent,
})
export class AppModule {
  constructor(private upgrade: UpgradeModule) { }
  ngDoBootstrap() {
    this.upgrade.bootstrap(document.documentElement, ['phonecatApp']);
  }
}