angular-cn/aio/content/guide/browser-support.md

# Browser support

Angular supports most recent browsers. This includes the following specific versions:

<table>
  <tr>
    <th>Browser</th>
    <th>Supported versions</th>
  </tr>
  <tr>
    <td>Chrome</td>
    <td>latest</td>
  </tr>
  <tr>
    <td>Firefox</td>
    <td>latest and extended support release (ESR)</td>
  </tr>
  <tr>
    <td>Edge</td>
    <td>2 most recent major versions</td>
  </tr>
  <tr>
    <td>IE</td>
    <td>
      11<br>
      <em>*deprecated, see the <a href="guide/deprecations#internet-explorer-11">deprecations guide</a></em>
    </td>
  </tr>
  <tr>
    <td>Safari</td>
    <td>2 most recent major versions</td>
  </tr>
  <tr>
    <td>iOS</td>
    <td>2 most recent major versions</td>
  </tr>
  <tr>
    <td>Android</td>
    <td>Q (10.0), Pie (9.0), Oreo (8.0), Nougat (7.0)</td>
  </tr>
</table>


<div class="alert is-helpful">

Angular's continuous integration process runs unit tests of the framework on all of these browsers for every pull request,
using [Sauce Labs](https://saucelabs.com/) and
[BrowserStack](https://www.browserstack.com/).

</div>


{@a ie11}
## Configuring Angular CLI for compatibility with IE11

While Angular supports all browsers listed above, in order to improve the build times and output,  Angular CLI applications don't support IE11 by default.

Angular CLI uses [`browserlist`](https://github.com/browserslist/browserslist) to configure browser support for applications.

You can enable the IE11 support by following the instructions in the `.browserslistrc` file at the root of your project.

## Polyfills

Angular is built on the latest standards of the web platform.
Targeting such a wide range of browsers is challenging because they do not support all features of modern browsers.
You compensate by loading polyfill scripts ("polyfills") for the browsers that you must support.
The [table below](#polyfill-libs) identifies most of the polyfills you might need.

<div class="alert is-important">

The suggested polyfills are the ones that run full Angular applications.
You may need additional polyfills to support features not covered by this list.
Note that polyfills cannot magically transform an old, slow browser into a modern, fast one.

</div>

In Angular CLI version 8 and higher, applications are built using *differential loading*, a strategy where the CLI builds two separate bundles as part of your deployed application.

* The first bundle contains modern ES2015 syntax, takes advantage of built-in support in modern browsers, ships less polyfills, and results in a smaller bundle size.

* The second bundle contains code in the old ES5 syntax, along with all necessary polyfills. This results in a larger bundle size, but supports older browsers.

This strategy allows you to continue to build your web application to support multiple browsers, but only load the necessary code that the browser needs.
For more information about how this works, see [Differential Loading](guide/deployment#differential-loading) in the [Deployment guide](guide/deployment).

## Enabling polyfills with CLI projects

The [Angular CLI](cli) provides support for polyfills.
If you are not using the CLI to create your projects, see [Polyfill instructions for non-CLI users](#non-cli).

When you create a project with the `ng new` command, a `src/polyfills.ts` configuration file is created as part of your project folder.
This file incorporates the mandatory and many of the optional polyfills as JavaScript `import` statements.

* The npm packages for the [_mandatory_ polyfills](#polyfill-libs) (such as `zone.js`) are installed automatically for you when you create your project with `ng new`, and their corresponding `import` statements are already enabled in the `src/polyfills.ts` configuration file.

* If you need an _optional_ polyfill, you must install its npm package, then uncomment or create the corresponding import statement in the `src/polyfills.ts` configuration file.

For example, if you need the optional [web animations polyfill](https://caniuse.com/web-animation), you could install it with `npm`, using the following command (or the `yarn` equivalent):

<code-example language="sh">
  # install the optional web animations polyfill
  npm install --save web-animations-js
</code-example>

You can then add the import statement in the `src/polyfills.ts` file.
For many polyfills, you can simply un-comment the corresponding `import` statement in the file, as in the following example.

<code-example header="src/polyfills.ts">
  /**
  * Required to support Web Animations `@angular/platform-browser/animations`.
  * Needed for: All but Chrome, Firefox and Opera. https://caniuse.com/web-animation
  **/
  import 'web-animations-js';  // Run `npm install --save web-animations-js`.
</code-example>

If the polyfill you want is not already in `polyfills.ts` file, add the `import` statement by hand.


{@a polyfill-libs}

### Mandatory polyfills
These are the polyfills required to run an Angular application on each supported browser:

<table>
  <tr style="vertical-align: top">
    <th>Browsers (Desktop & Mobile)</th>
    <th>Polyfills Required</th>
  </tr>
  <tr style="vertical-align: top">
    <td>
      Chrome, Firefox, Edge, <br>
      Safari, Android, IE 11
    </td>
    <td>
      <a href="guide/browser-support#core-es6">ES2015</a>
    </td>
  </tr>
</table>

### Optional browser features to polyfill

Some features of Angular may require additional polyfills.

<table>
  <tr style="vertical-align: top">
    <th>Feature</th>
    <th>Polyfill</th>
    <th style="width: 50%">Browsers (Desktop & Mobile)</th>
  </tr>
  <tr style="vertical-align: top">
    <td>
      <a href="api/animations/AnimationBuilder">AnimationBuilder</a>
      (Standard animation support does not require polyfills.)
    </td>
    <td>
      <a href="guide/browser-support#web-animations">Web Animations</a>
    </td>
    <td>
      <p>If AnimationBuilder is used, enables scrubbing
      support for IE/Edge and Safari.
      (Chrome and Firefox support this natively).</p>
    </td>
  </tr>

  <tr style="vertical-align: top">
    <td>
      <a href="api/common/NgClass">NgClass</a> on SVG elements
    </td>
    <td>
      <a href="guide/browser-support#classlist">classList</a>
    </td>
    <td>
      IE 11
    </td>
  </tr>

  <tr style="vertical-align: top">
    <td>
      <a href="guide/router">Router</a> when using <a href="guide/router#location-strategy">hash-based routing</a>
    </td>
    <td>
      <a href="guide/browser-support#core-es7-array">ES7/array</a>
    </td>
    <td>
      IE 11
    </td>
  </tr>
</table>

### Suggested polyfills

The following polyfills are used to test the framework itself. They are a good starting point for an application.


<table>
  <tr>
    <th>
      Polyfill
    </th>
    <th>
      License
    </th>
    <th>
      Size*
    </th>
  </tr>
  <tr>
    <td>
      <a id='core-es7-array' href="https://github.com/zloirock/core-js/tree/v2/fn/array">ES7/array</a>
    </td>
    <td>
      MIT
    </td>
    <td>
      0.1KB
    </td>
  </tr>
  <tr>
    <td>
      <a id='core-es6' href="https://github.com/zloirock/core-js">ES2015</a>
    </td>
    <td>
      MIT
    </td>
    <td>
      27.4KB
    </td>
  </tr>

  <tr>
    <td>
      <a id='classlist' href="https://github.com/eligrey/classList.js">classList</a>
    </td>
    <td>
      Public domain
    </td>
    <td>
      1KB
    </td>
  </tr>
  <tr>
    <td>
       <a id='web-animations' href="https://github.com/web-animations/web-animations-js">Web Animations</a>
    </td>
    <td>
      Apache
    </td>
    <td>
      14.8KB
    </td>
  </tr>
</table>


\* Figures are for minified and gzipped code,
computed with the [closure compiler](https://closure-compiler.appspot.com/home).

{@a non-cli}

## Polyfills for non-CLI users

If you are not using the CLI, add your polyfill scripts directly to the host web page (`index.html`).

For example:

<code-example header="src/index.html" language="html">
  &lt;!-- pre-zone polyfills -->
  &lt;script src="node_modules/core-js/client/shim.min.js">&lt;/script>
  &lt;script src="node_modules/web-animations-js/web-animations.min.js">&lt;/script>
  &lt;script>
    /**
     * you can configure some zone flags which can disable zone interception for some
     * asynchronous activities to improve startup performance - use these options only
     * if you know what you are doing as it could result in hard to trace down bugs..
     */
    // __Zone_disable_requestAnimationFrame = true; // disable patch requestAnimationFrame
    // __Zone_disable_on_property = true; // disable patch onProperty such as onclick
    // __zone_symbol__UNPATCHED_EVENTS = ['scroll', 'mousemove']; // disable patch specified eventNames
    /*
     * in IE/Edge developer tools, the addEventListener will also be wrapped by zone.js
     * with the following flag, it will bypass `zone.js` patch for IE/Edge
     */
    // __Zone_enable_cross_context_check = true;
  &lt;/script>
  &lt;!-- zone.js required by Angular -->
  &lt;script src="node_modules/zone.js/bundles/zone.umd.js">&lt;/script>
  &lt;!-- application polyfills -->
</code-example>