# Deployment

# 部署

When you are ready to deploy your Angular application to a remote server, you have various options for
deployment. 

当你准备把 Angular 应用部署到远程服务器上时，有很多关于部署的选项。

{@a dev-deploy}

{@a copy-files}

## Simplest deployment possible

## 最简化的部署方式

For the simplest deployment, build for development and copy the output directory to a web server.

最简化的部署方式就是为开发环境构建，并把其输出复制到 Web 服务器上。

1. Start with the development build:

   使用开发环境进行构建

  <code-example language="none" class="code-shell">
    ng build
  </code-example>

2. Copy _everything_ within the output folder (`dist/` by default) to a folder on the server.

   把输出目录（默认为 `dist/`）下的*每个文件*都复制到到服务器上的某个目录下。

3. Configure the server to redirect requests for missing files to `index.html`.
Learn more about server-side redirects [below](#fallback).

   配置服务器，让缺失的文件都重定向到 `index.html` 上。
   欲知详情，参见[稍后](#fallback)的服务端重定向部分。

This is _not_ a production deployment. It's not optimized, and it won't be fast for users.
It might be good enough for sharing your progress and ideas internally with managers, teammates, and other stakeholders. For the next steps in deployment, see [Optimize for production](#optimize).

这*不是*生产环境部署。它没有优化过，对最终用户来说也不快。
但是，这足够用来跟管理者、团队成员和其它涉众在内部分享你的进度和想法了。
部署的下一个步骤，参见[为生产环境优化](#optimize)。

{@a deploy-to-github}

## Deploy to GitHub pages

## 发布到 GitHub pages（页面服务）

Another simple way to deploy your Angular app is to use [GitHub Pages](https://help.github.com/articles/what-is-github-pages/).

另一种发布 Angular 应用的简单途径是使用 [GitHub Pages](https://help.github.com/articles/what-is-github-pages/)。

1. You need to [create a GitHub account](https://github.com/join) if you don't have one, and then [create a repository](https://help.github.com/articles/create-a-repo/) for your project. 
Make a note of the user name and project name in GitHub.

   你需要[创建一个 GitHub 账号](https://github.com/join)（如果没有的话），然后为你的项目[创建一个仓库](https://help.github.com/articles/create-a-repo/)。记下 GitHub 中的用户名和项目名。

1. Build your project using Github project name, with the Angular CLI command [`ng build`](cli/build) and the options shown here:

   使用 Angular CLI 命令 [`ng build`](cli/build) 来构建这个 GitHub 项目，选项如下：

   <code-example language="none" class="code-shell">
     ng build --prod --output-path docs --base-href <project_name>
    </code-example>

1. When the build is complete, make a copy of `docs/index.html` and name it `docs/404.html`. 

   当构建完成时，把 `docs/index.html` 复制为 `docs/404.html`。

1. Commit your changes and push. 

   提交你的更改，并推送。

1. On the GitHub project page, configure it to [publish from the docs folder](https://help.github.com/articles/configuring-a-publishing-source-for-github-pages/#publishing-your-github-pages-site-from-a-docs-folder-on-your-master-branch).

   在 GitHub 的项目页中，把该项目配置为[从 docs 目录下发布](https://help.github.com/articles/configuring-a-publishing-source-for-github-pages/#publishing-your-github-pages-site-from-a-docs-folder-on-your-master-branch)。

You can see your deployed page at `https://<user_name>.github.io/<project_name>/`.

你可以到 `https://<user_name>.github.io/<project_name>/` 中查看部署好的页面。

<div class="alert is-helpful>

 Check out [angular-cli-ghpages](https://github.com/angular-buch/angular-cli-ghpages), a full featured package that does all this for you and has extra functionality.

 参见 [angular-cli-ghpages](https://github.com/angular-buch/angular-cli-ghpages)，这个包用到了全部这些特性，还提供了一些额外功能。

</div>

<hr>

{@a server-configuration}

## Server configuration

## 服务端配置

This section covers changes you may have make to the server or to files deployed to the server.

这一节涵盖了你可能对服务器或准备部署到服务器的文件要做的那些修改。

{@a fallback}

### Routed apps must fallback to `index.html`

### 带路由的应用必须以 `index.html` 作为后备页面

Angular apps are perfect candidates for serving with a simple static HTML server.
You don't need a server-side engine to dynamically compose application pages because
Angular does that on the client-side.

Angular 应用很适合用简单的静态 HTML 服务器提供服务。
你不需要服务端引擎来动态合成应用页面，因为 Angular 会在客户端完成这件事。

If the app uses the Angular router, you must configure the server
to return the application's host page (`index.html`) when asked for a file that it does not have.

如果该应用使用 Angular 路由器，你就必须配置服务器，让它对不存在的文件返回应用的宿主页(`index.html`)。

{@a deep-link}

A routed application should support "deep links".
A _deep link_ is a URL that specifies a path to a component inside the app.
For example, `http://www.mysite.com/heroes/42` is a _deep link_ to the hero detail page
that displays the hero with `id: 42`.

带路由的应用应该支持“深链接”。
所谓*深链接*就是指一个 URL，它用于指定到应用内某个组件的路径。
比如，`http://www.mysite.com/heroes/42` 就是一个到英雄详情页面的*深链接*，用于显示 `id: 42` 的英雄。

There is no issue when the user navigates to that URL from within a running client.
The Angular router interprets the URL and routes to that page and hero.

当用户从运行中的客户端应用导航到这个 URL 时，这没问题。
Angular 路由器会拦截这个 URL，并且把它路由到正确的页面。

But clicking a link in an email, entering it in the browser address bar,
or merely refreshing the browser while on the hero detail page &mdash;
all of these actions are handled by the browser itself, _outside_ the running application.
The browser makes a direct request to the server for that URL, bypassing the router.

但是，当从邮件中点击链接或在浏览器地址栏中输入它或仅仅在英雄详情页刷新下浏览器时，所有这些操作都是由浏览器本身处理的，在应用的控制范围之外。
浏览器会直接向服务器请求那个 URL，路由器没机会插手。

A static server routinely returns `index.html` when it receives a request for `http://www.mysite.com/`.
But it rejects `http://www.mysite.com/heroes/42` and returns a `404 - Not Found` error *unless* it is
configured to return `index.html` instead.

静态服务器会在收到对 `http://www.mysite.com/` 的请求时返回 `index.html`，但是会拒绝对 `http://www.mysite.com/heroes/42` 的请求，
并返回一个 `404 - Not Found` 错误，除非，它被配置成了返回 `index.html`。

#### Fallback configuration examples

#### 后备页面配置范例

There is no single configuration that works for every server.
The following sections describe configurations for some of the most popular servers.
The list is by no means exhaustive, but should provide you with a good starting point.

没有一种配置可以适用于所有服务器。
后面这些部分会描述对常见服务器的配置方式。
这个列表虽然不够详尽，但可以为你提供一个良好的起点。

#### Development servers

#### 开发服务器

During development, the [`ng serve`](cli/serve) CLI command lets you run your app in a local browser. 
The CLI recompiles the application each time you save a file, 
and reloads the browser with the newly compiled application. 

在开发期间，CLI 命令 [`ng serve`](cli/serve) 能让你在本地浏览器中运行你的应用。
每当你保存文件时，CLI 就会重新编译该应用，并刷新浏览器，来加载最新编译的应用。

The app is hosted in local memory and served on `http://localhost:4200/`, using [webpack-dev-server](https://webpack.js.org/guides/development/#webpack-dev-server).

该应用运行在本地内存里，并使用 [webpack-dev-server](https://webpack.js.org/guides/development/#webpack-dev-server) 来在 `http://localhost:4200/` 端口上提供服务。

{@a serve-from-disk}

Later in development, you might want a closer approximation of how your app will behave when deployed. 
You can output your distribution folder (`dist`) to disk, but you need to install a different web server. 
Try installing  [lite-server](https://github.com/johnpapa/lite-server); like `webpack-dev-server`, it can automatically reload your browser when you write new files.

在开发的后期阶段，你可能会希望让应用更接近部署后的行为方式。
这时，你可以把发布目录（`dist`）输出到磁盘上，但还要安装另一个 Web 服务器。
可以尝试安装 [lite-server](https://github.com/johnpapa/lite-server)，像 `webpack-dev-server` 一样，当你修改了文件时，它可以自动刷新浏览器。

To get the live-reload experience, you will need to run two terminals. 
The first runs the build in a watch mode and compiles the application to the `dist` folder. 
The second runs the web server against the `dist` folder. 
The combination of these two processes provides the same behavior as `ng serve`.

要想获得实时刷新（live-reload）的体验，你需要运行两个终端。
第一个在监视模式下运行 `build` 命令，把应用随时编译到 `dist` 目录下。
第二个针对 `dist` 目录运行 Web 服务器。
这两个过程组合起来，提供了与 `ng serve` 相同的行为。

1. Start the build in terminal A:

   在终端 A 中启动构建：

<code-example language="none" class="code-shell">
ng build --watch
</code-example>

1. Start the web server in terminal B:

   在终端 B 中启动 Web 服务器：

<code-example language="none" class="code-shell">
lite-server --baseDir="dist"
</code-example>

The default browser opens to the appropriate URL.

默认的浏览器会打开相应的 URL。

* [Lite-Server](https://github.com/johnpapa/lite-server): the default dev server installed with the
[Quickstart repo](https://github.com/angular/quickstart) is pre-configured to fallback to `index.html`.

   [Lite-Server](https://github.com/johnpapa/lite-server)是["快速上手"仓库](https://github.com/angular/quickstart)中安装的默认开发服务器，它被预先配置为回退到 `index.html`。

* [Webpack-Dev-Server](https://github.com/webpack/webpack-dev-server):  setup the
`historyApiFallback` entry in the dev server options as follows:

   [Webpack-Dev-Server](https://github.com/webpack/webpack-dev-server)在开发服务器的配置中设置了 `historyApiFallback`，代码如下：

  <code-example>
    historyApiFallback: {
      disableDotRule: true,
      htmlAcceptHeaders: ['text/html', 'application/xhtml+xml']
    }
  </code-example>

#### Production servers

#### 生产服务器

* [Apache](https://httpd.apache.org/): add a
[rewrite rule](http://httpd.apache.org/docs/current/mod/mod_rewrite.html) to the `.htaccess` file as shown
  (https://ngmilk.rocks/2015/03/09/angularjs-html5-mode-or-pretty-urls-on-apache-using-htaccess/):

   [Apache](https://httpd.apache.org/)：在 `.htaccess` 文件中添加一个[重写规则](http://httpd.apache.org/docs/current/mod/mod_rewrite.html)，
代码如下（[出处](https://ngmilk.rocks/2015/03/09/angularjs-html5-mode-or-pretty-urls-on-apache-using-htaccess/)）：

  <code-example format=".">
    RewriteEngine On
    &#35 If an existing asset or directory is requested go to it as it is
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -f [OR]
    RewriteCond %{DOCUMENT_ROOT}%{REQUEST_URI} -d
    RewriteRule ^ - [L]

    &#35 If the requested resource doesn't exist, use index.html
    RewriteRule ^ /index.html
  </code-example>

* [Nginx](http://nginx.org/): use `try_files`, as described in
[Front Controller Pattern Web Apps](https://www.nginx.com/resources/wiki/start/topics/tutorials/config_pitfalls/#front-controller-pattern-web-apps),
modified to serve `index.html`:

   [NGinx](http://nginx.org/)：使用 `try_files` 指向 `index.html`，详细描述见[Web 应用的前端控制器模式](https://www.nginx.com/resources/wiki/start/topics/tutorials/config_pitfalls/#front-controller-pattern-web-apps)。

  <code-example format=".">
    try_files $uri $uri/ /index.html;
  </code-example>

* [IIS](https://www.iis.net/): add a rewrite rule to `web.config`, similar to the one shown
[here](http://stackoverflow.com/a/26152011/2116927):

   [IIS](https://www.iis.net/)：往 `web.config` 中添加一条重写规则，类似于[这里](http://stackoverflow.com/a/26152011/2116927)：

  <code-example format='.'>
    &lt;system.webServer&gt;
      &lt;rewrite&gt;
        &lt;rules&gt;
          &lt;rule name="Angular Routes" stopProcessing="true"&gt;
            &lt;match url=".*" /&gt;
            &lt;conditions logicalGrouping="MatchAll"&gt;
              &lt;add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" /&gt;
              &lt;add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" /&gt;
            &lt;/conditions&gt;
            &lt;action type="Rewrite" url="/index.html" /&gt;
          &lt;/rule&gt;
        &lt;/rules&gt;
      &lt;/rewrite&gt;
    &lt;/system.webServer&gt;

  </code-example>

* [GitHub Pages](https://pages.github.com/): you can't
[directly configure](https://github.com/isaacs/github/issues/408)
the GitHub Pages server, but you can add a 404 page.
Copy `index.html` into `404.html`.
It will still be served as the 404 response, but the browser will process that page and load the app properly.
It's also a good idea to
[serve from `docs/` on master](https://help.github.com/articles/configuring-a-publishing-source-for-github-pages/#publishing-your-github-pages-site-from-a-docs-folder-on-your-master-branch)
and to
[create a `.nojekyll` file](https://www.bennadel.com/blog/3181-including-node-modules-and-vendors-folders-in-your-github-pages-site.htm)

   [GitHub 页面服务](https://pages.github.com/)：你没办法[直接配置](https://github.com/isaacs/github/issues/408) Github 的页面服务，但可以添加一个 404 页，只要把 `index.html` 复制到 `404.html` 就可以了。
  它仍然会给出一个 404 响应，但是浏览器将会正确处理该页，并正常加载该应用。
  使用[在主分支的 `docs/` 下启动服务](https://help.github.com/articles/configuring-a-publishing-source-for-github-pages/#publishing-your-github-pages-site-from-a-docs-folder-on-your-master-branch)
  并[创建一个 `.nojekyll` 文件](https://www.bennadel.com/blog/3181-including-node-modules-and-vendors-folders-in-your-github-pages-site.htm)也是一个好办法。

* [Firebase hosting](https://firebase.google.com/docs/hosting/): add a
[rewrite rule](https://firebase.google.com/docs/hosting/url-redirects-rewrites#section-rewrites).

   [Firebase 主机服务](https://firebase.google.com/docs/hosting/)：添加一条[重写规则](https://firebase.google.com/docs/hosting/url-redirects-rewrites#section-rewrites)。

  <code-example format=".">
    "rewrites": [ {
      "source": "**",
      "destination": "/index.html"
    } ]

  </code-example>

{@a cors}

### Requesting services from a different server (CORS)

### 请求来自另一个服务器的服务（CORS）

Angular developers may encounter a
<a href="https://en.wikipedia.org/wiki/Cross-origin_resource_sharing" title="Cross-origin resource sharing">
<i>cross-origin resource sharing</i></a> error when making a service request (typically a data service request)
to a server other than the application's own host server.
Browsers forbid such requests unless the server permits them explicitly.

Angular 开发者在向与该应用的宿主服务器不同域的服务器发起请求时，可能会遇到一种<a href="https://en.wikipedia.org/wiki/Cross-origin_resource_sharing" target="_blank" title="Cross-origin resource sharing"><i>跨域资源共享（CORS）</i></a>错误。
浏览器会阻止该请求，除非得到那台服务器的明确许可。

There isn't anything the client application can do about these errors.
The server must be configured to accept the application's requests.
Read about how to enable CORS for specific servers at
<a href="http://enable-cors.org/server.html" title="Enabling CORS server">enable-cors.org</a>.

客户端应用对这种错误无能为力。
服务器必须配置成可以接受来自该应用的请求。
要了解如何对特定的服务器开启 CORS，参见<a href="http://enable-cors.org/server.html" target="_blank" title="Enabling CORS server">enable-cors.org</a>。

<hr>

{@a optimize}

## Optimize for production

## 为生产环境优化

Although deploying directly from the development environment works, 
you can generate an optimized build with additional CLI command line flags,
starting with `--prod`.

虽然也可以直接用开发环境部署，但也可以使用其它的 CLI 命令行标志来生成优化过的构建成果，我们先从 `--prod` 开始讲。

### Build with _--prod_

### 使用*--prod*构建

<code-example language="none" class="code-shell">
  ng build --prod
</code-example>

The `--prod` _meta-flag_ engages the following optimization features.

`--prod` 标志具有如下优化特性。

* [Ahead-of-Time (AOT) Compilation](guide/aot-compiler): pre-compiles Angular component templates.

  [预先(AOT)编译](guide/aot-compiler)：预编译 Angular 的组件模板。

* [Production mode](#enable-prod-mode): deploys the production environment which enables _production mode_.

  [生产模式](#enable-prod-mode)：部署到启用了*生产模式*的生产环境。

* Bundling: concatenates your many application and library files into a few bundles.

  打包：把你的多个应用于库文件拼接到少量包（bundle）中。

* Minification: removes excess whitespace, comments, and optional tokens.

  最小化：删除多余的空格、注释和可选令牌。

* Uglification: rewrites code to use short, cryptic variable and function names.

  混淆/丑化：重写代码，使用简短的、不容易理解的变量名和函数名。

* Dead code elimination: removes unreferenced modules and much unused code.

  消除死代码：删除未引用过的模块和很多未用到的代码。

The remaining [copy deployment steps](#copy-files) are the same as before.

其余的[复制等部署步骤](#copy-files)步骤和以前的一样。

See [`ng build`](cli/build) for more about CLI build options and what they do.

要了解关于 CLI 构建选项及其作用的更多知识，参见 [`ng build`](cli/build)。

{@a enable-prod-mode}

### Enable production mode

### 启用生产模式

Angular apps run in development mode by default, as you can see by the following message on the browser
console:

Angular 应用默认运行在开发模式下，你可以在浏览器的控制台中看到如下信息：

<code-example format="nocode">
  Angular is running in the development mode. Call enableProdMode() to enable the production mode.
</code-example>

Switching to _production mode_ can make it run faster by disabling development specific checks such as the dual change detection cycles.

切换到*生产模式*可以通过禁用开发阶段特有的检查（比如双重变更检测周期）来让它运行得更快。

Building for production (or appending the `--environment=prod` flag) enables _production mode_
Look at the CLI-generated `main.ts` to see how this works.

为生产环境构建（添加 `--environment=prod` 标识）可以启用*生产模式*。
阅读 CLI 生成的 `main.ts` 以了解它的工作原理。

{@a lazy-loading}

### Lazy loading

### 惰性加载

You can dramatically reduce launch time by only loading the application modules that
absolutely must be present when the app starts.

通过只加载应用启动时绝对必须的那些模块，你可以戏剧性的缩短应用启动时间。

Configure the Angular Router to defer loading of all other modules (and their associated code), either by
[waiting until the app has launched](guide/router#preloading  "Preloading")
or by [_lazy loading_](guide/router#asynchronous-routing "Lazy loading")
them on demand.

可以配置 Angular 的路由器，来推迟所有其它模块（及其相关代码）的加载时机，方法有[一直等到应用启动完毕](guide/router#preloading  "Preloading")，或者当用到时才按需[*惰性加载*](guide/router#asynchronous-routing "Lazy loading")。

<div class="alert is-helpful>

#### Don't eagerly import something from a lazy-loaded module

#### 不要急性（eagerly）导入来自惰性加载模块中的任何东西

If you mean to lazy-load a module, be careful not import it
in a file that's eagerly loaded when the app starts (such as the root `AppModule`).
If you do that, the module will be loaded immediately.

如果要惰性加载某个模块，就要小心别在应用启动时要急性加载的模块（比如根模块 `AppModule`）中导入它。
如果那么做，该模块就会立刻加载起来。

The bundling configuration must take lazy loading into consideration.
Because lazy-loaded modules aren't imported in JavaScript, bundlers exclude them by default.
Bundlers don't know about the router configuration and can't create separate bundles for lazy-loaded modules. 
You would have to create these bundles manually.

配置打包方式时必须考虑惰性加载。
因为默认情况下惰性加载的模块没有在 JavaScript 中导入过，因此打包器默认会排除它们。
打包器不认识路由器配置，也就不能为惰性加载的模块创建独立的包。
你必须手动创建这些包。

The CLI runs the
[Angular Ahead-of-Time Webpack Plugin](https://github.com/angular/angular-cli/tree/master/packages/%40ngtools/webpack)
which automatically recognizes lazy-loaded `NgModules` and creates separate bundles for them.

CLI 会运行 [Angular Ahead-of-Time Webpack 插件](https://github.com/angular/angular-cli/tree/master/packages/%40ngtools/webpack)，它会自动识别出惰性加载的 `NgModules`，并为它们创建独立的包。

</div>

{@a measure}

### Measure performance

### 测量性能

You can make better decisions about what to optimize and how when you have a clear and accurate understanding of
what's making the application slow.
The cause may not be what you think it is.
You can waste a lot of time and money optimizing something that has no tangible benefit or even makes the app slower.
You should measure the app's actual behavior when running in the environments that are important to you.

如果你对哪些东西拖慢了应用有更加清晰、精确的了解，就可以更好地决定优化什么以及如何优化。
慢的原因可能和你所想的不一样。
你可能花费了大量的时间和金钱来优化一些实际上无关紧要的东西，甚至可能让应用变得更慢。
你应该测量应用在运行环境中的实际行为，这才是最重要的。

The
<a href="https://developers.google.com/web/tools/chrome-devtools/network-performance/understanding-resource-timing" title="Chrome DevTools Network Performance">
Chrome DevTools Network Performance page</a> is a good place to start learning about measuring performance.

<a href="https://developers.google.com/web/tools/chrome-devtools/network-performance/understanding-resource-timing" title="Chrome DevTools Network Performance">
Chrome DevTools 的网络和性能页</a>是你开始学习如何测量性能的好地方。

The [WebPageTest](https://www.webpagetest.org/) tool is another good choice
that can also help verify that your deployment was successful.

[WebPageTest](https://www.webpagetest.org/)工具是另一个不错的选择，它还能帮你验证这次部署是否成功。

{@a inspect-bundle}

### Inspect the bundles

### 检查发布包

The <a href="https://github.com/danvk/source-map-explorer/blob/master/README.md">source-map-explorer</a>
tool is a great way to inspect the generated JavaScript bundles after a production build.

<a href="https://github.com/danvk/source-map-explorer/blob/master/README.md">source-map-explorer</a> 工具可以帮你在生产环境构建之后探查 JavaScript 包。

Install `source-map-explorer`:

安装 `source-map-explorer`：

<code-example language="none" class="code-shell">
  npm install source-map-explorer --save-dev
</code-example>

Build your app for production _including the source maps_

为生产环境构建应用，包括源码映射表（source map）

<code-example language="none" class="code-shell">
  ng build --prod --source-map
</code-example>

List the generated bundles in the `dist/` folder.

在 `dist/` 目录下列出生成的包。

<code-example language="none" class="code-shell">
  ls dist/*.bundle.js
</code-example>

Run the explorer to generate a graphical representation of one of the bundles.
The following example displays the graph for the _main_ bundle.

运行浏览器来生成其中一个包的图形化表示。
下面的例子展示了 `main` 包的图表。

<code-example language="none" class="code-shell">
  node_modules/.bin/source-map-explorer dist/main.*.bundle.js
</code-example>

The `source-map-explorer` analyzes the source map generated with the bundle and draws a map of all dependencies,
showing exactly which classes are included in the bundle.

`source-map-explorer` 会分析与包一期生成的 source map，并画出所有依赖的地图，精确展示哪些类包含在哪个包中。

Here's the output for the _main_ bundle of the QuickStart.

下面是 "快速上手" 应用中 `main` 包的输出。

<figure>
  <img src="generated/images/guide/cli-quickstart/quickstart-sourcemap-explorer.png" alt="quickstart sourcemap explorer">
</figure>

{@a base-tag}

## The `base` tag

## `base` 标签

The HTML [_&lt;base href="..."/&gt;_](/guide/router)
specifies a base path for resolving relative URLs to assets such as images, scripts, and style sheets.
For example, given the `<base href="/my/app/">`, the browser resolves a URL such as `some/place/foo.jpg`
into a server request for `my/app/some/place/foo.jpg`.
During navigation, the Angular router uses the _base href_ as the base path to component, template, and module files.

HTML 的 [_&lt;base href="..."/&gt;_](/guide/router) 标签指定了用于解析静态文件（如图片、脚本和样式表）相对地址的基地址。
比如，对于 `<base href="/my/app/">`，浏览器就会把 `some/place/foo.jpg` 这样的 URL 解析成到 `my/app/some/place/foo.jpg` 的请求。
在导航期间，Angular 路由器使用 *base href* 作为到组件模板文件和模块文件的基地址。

<div class="alert is-helpful">

See also the [*APP_BASE_HREF*](api/common/APP_BASE_HREF "API: APP_BASE_HREF") alternative.

另一种方式参见 [*APP_BASE_HREF*](api/common/APP_BASE_HREF "API: APP_BASE_HREF")。

</div>

In development, you typically start the server in the folder that holds `index.html`.
That's the root folder and you'd add `<base href="/">` near the top of `index.html` because `/` is the root of the app.

在开发期间，你通常会在存有 `index.html` 的目录下启动开发服务器。
那就是根目录，你要在 `index.html` 的顶部附近添加 `<base href="/">`，因为 `/` 就是该应用的根路径。

But on the shared or production server, you might serve the app from a subfolder.
For example, when the URL to load the app is something like `http://www.mysite.com/my/app/`,
the subfolder is `my/app/` and you should add `<base href="/my/app/">` to the server version of the `index.html`.

但是在共享或生产服务器上，你可能会在子目录下启动服务器。
比如，当前应用的加载地址可能类似于 `http://www.mysite.com/my/app/`，这里的子目录就是 `my/app/`。所以你就要往服务端版本的 `index.html` 中添加 `<base href="/my/app/">`。

When the `base` tag is mis-configured, the app fails to load and the browser console displays `404 - Not Found` errors
for the missing files. Look at where it _tried_ to find those files and adjust the base tag appropriately.

这里如果不配置 `base` 标签，应用就会失败，并在浏览器的控制台中为缺失的文件显示一个 `404 - Not Found` 错误。看看它*试图*从哪里去查找那些文件，并据此调整 base 标签。

## Building and serving for deployment

## 为部署而构建和启动服务器

When you are designing and developing applications, you typically use `ng serve` to build your app for fast, local, iterative development. 
When you are ready to deploy, however, you must use the `ng build` command to build the app and deploy the build artifacts elsewhere.

在设计和开发应用程序时，通常使用 `ng serve` 来构建应用，已进行快速的、本地的、迭代式的开发。
不过，当准备部署时，你必须使用 `ng build` 命令来构建应用，并在别处部署构建成果。

Both `ng build` and `ng serve` clear the output folder before they build the project, but only the `ng build` command writes the generated build artifacts to the output folder.

在构建之前，`ng build` 和 `ng serve` 都会清空输出目录，但是只有 `ng build` 命令才会把生成的构建成果写入到输出目录下。

<div class="alert is-helpful">

The output folder is  `dist/` by default.
To output to a different folder, change the `outputPath` in `angular.json`.

输出目录默认为 `dist/`。
要想输出到其它目录，请修改 `angular.json` 中的 `outputPath`。

</div>

The `ng serve` command builds, watches, and serves the application from local memory, using a local development server.
When you have deployed your app to another server, however, you might still want to serve the app so that you can continue to see changes that you make in it. 
You can do this by adding the `--watch` option to the `ng build` command.

`ng serve` 命令会构建、监视并使用本地开发服务器从内存中提供网站服务。
但是，当你将应用部署到其它服务器时，你可能希望仍然能持续看到你对该应用所做的修改。这时候，你可以为 `ng build` 命令添加 `--watch` 选项来做到这一点。

```
ng build --watch
```
Like the `ng serve` command, this regenerates output files when source files change. 

像 `ng serve` 命令一样，当源码文件发生变化时，它会重新生成输出文件。

For complete details of the CLI commands, see the [CLI command reference](cli).

要了解 CLI 命令的详细信息，参见 [CLI 命令参考手册](cli)。