130 lines
5.2 KiB
Markdown
130 lines
5.2 KiB
Markdown
# JavaScript Modules vs. NgModules
|
||
|
||
# JavaScript 模块 vs. NgModule
|
||
|
||
#### Prerequisites
|
||
|
||
#### 前提条件
|
||
|
||
A basic understanding of [JavaScript/ECMAScript modules](https://hacks.mozilla.org/2015/08/es6-in-depth-modules/).
|
||
|
||
对 [JavaScript/ECMAScript 模块](https://hacks.mozilla.org/2015/08/es6-in-depth-modules/) 有基本的了解。
|
||
|
||
<hr>
|
||
|
||
JavaScript and Angular use modules to organize code, and
|
||
though they organize it differently, Angular apps rely on both.
|
||
|
||
JavaScript 和 Angular 都使用模块来组织代码，虽然它们的组织形式不同，但 Angular 的应用会同时依赖两者。
|
||
|
||
## JavaScript modules
|
||
|
||
## JavaScript 模块
|
||
|
||
In JavaScript, modules are individual files with JavaScript code in them. To make what’s in them available, you write an export statement, usually after the relevant code, like this:
|
||
|
||
在 JavaScript 中，模块是内含 JavaScript 代码的独立文件。要让其中的东西可用，你要写一个导出语句，通常会放在相应的代码之后，类似这样：
|
||
|
||
```typescript
|
||
|
||
export class AppComponent { ... }
|
||
|
||
```
|
||
|
||
Then, when you need that file’s code in another file, you import it like this:
|
||
|
||
然后，当你在其它文件中需要这个文件的代码时，要像这样导入它：
|
||
|
||
```typescript
|
||
|
||
import { AppComponent } from './app.component';
|
||
|
||
```
|
||
|
||
JavaScript modules help you namespace, preventing accidental global variables.
|
||
|
||
JavaScript 模块让你能为代码加上命名空间，防止因为全局变量而引起意外。
|
||
|
||
## NgModules
|
||
|
||
<!-- KW-- perMisko: let's discuss. This does not answer the question why it is different. Also, last sentence is confusing.-->
|
||
|
||
NgModules are classes decorated with `@NgModule`. The `@NgModule` decorator’s `imports` array tells Angular what other NgModules the current module needs. The modules in the `imports` array are different than JavaScript modules because they are NgModules rather than regular JavaScript modules. Classes with an `@NgModule` decorator are by convention kept in their own files, but what makes them an `NgModule` isn’t being in their own file, like JavaScript modules; it’s the presence of `@NgModule` and its metadata.
|
||
|
||
NgModule 是一些带有 `@NgModule` 装饰器的类。`@NgModule` 装饰器的 `imports` 数组会告诉 Angular 哪些其它的 NgModule 是当前模块所需的。
|
||
`imports` 数组中的这些模块与 JavaScript 模块不同，它们都是 NgModule 而不是常规的 JavaScript 模块。
|
||
带有 `@NgModule` 装饰器的类通常会习惯性地放在单独的文件中，但单独的文件并不像 JavaScript 模块那样作为必要条件，而是因为它带有 `@NgModule` 装饰器及其元数据。
|
||
|
||
The `AppModule` generated from the [Angular CLI](cli) demonstrates both kinds of modules in action:
|
||
|
||
[Angular CLI](cli) 生成的 `AppModule` 实际演示了这两种模块：
|
||
|
||
```typescript
|
||
|
||
/* These are JavaScript import statements. Angular doesn’t know anything about these. */
|
||
import { BrowserModule } from '@angular/platform-browser';
|
||
import { NgModule } from '@angular/core';
|
||
|
||
import { AppComponent } from './app.component';
|
||
|
||
/* The @NgModule decorator lets Angular know that this is an NgModule. */
|
||
@NgModule({
|
||
declarations: [
|
||
AppComponent
|
||
],
|
||
imports: [ /* These are NgModule imports. */
|
||
BrowserModule
|
||
],
|
||
providers: [],
|
||
bootstrap: [AppComponent]
|
||
})
|
||
export class AppModule { }
|
||
|
||
```
|
||
|
||
The NgModule classes differ from JavaScript module in the following key ways:
|
||
|
||
NgModule 类与 JavaScript 模块有下列关键性的不同：
|
||
|
||
* An NgModule bounds [declarable classes](guide/ngmodule-faq#q-declarable) only.
|
||
Declarables are the only classes that matter to the [Angular compiler](guide/ngmodule-faq#q-angular-compiler).
|
||
|
||
NgModule 只绑定了[*可声明的类*](guide/ngmodule-faq#q-declarable)，这些可声明的类只是供 [Angular 编译器](guide/ngmodule-faq#q-angular-compiler)用的。
|
||
|
||
* Instead of defining all member classes in one giant file as in a JavaScript module,
|
||
you list the module's classes in the `@NgModule.declarations` list.
|
||
|
||
与 JavaScript 类把它所有的成员类都放在一个巨型文件中不同，你要把该模块的类列在它的 `@NgModule.declarations` 列表中。
|
||
|
||
* An NgModule can only export the [declarable classes](guide/ngmodule-faq#q-declarable)
|
||
it owns or imports from other modules. It doesn't declare or export any other kind of class.
|
||
|
||
NgModule 只能导出[*可声明的类*](guide/ngmodule-faq#q-declarable)。这可能是它自己拥有的也可能是从其它模块中导入的。它不会声明或导出任何其它类型的类。
|
||
|
||
* Unlike JavaScript modules, an NgModule can extend the _entire_ application with services
|
||
by adding providers to the `@NgModule.providers` list.
|
||
|
||
与 JavaScript 模块不同，NgModule 可以通过把服务提供商加到 `@NgModule.providers` 列表中，来用服务扩展*整个*应用。
|
||
|
||
<hr />
|
||
|
||
## More on NgModules
|
||
|
||
## 关于 NgModule 的更多知识
|
||
|
||
For more information on NgModules, see:
|
||
|
||
要了解关于 NgModule 的更多知识，参见
|
||
|
||
* [Bootstrapping](guide/bootstrapping).
|
||
|
||
[引导启动](guide/bootstrapping)。
|
||
|
||
* [Frequently used modules](guide/frequent-ngmodules).
|
||
|
||
[常用模块](guide/frequent-ngmodules)。
|
||
|
||
* [Providers](guide/providers).
|
||
|
||
[服务提供商](guide/providers)。
|