# Configuring Browser Support

The official Nx plugins rely on [browserslist](https://github.com/browserslist/browserslist) for configuring application browser support. This affects builds, both production and development, and will decide on which transformations will be run on the code when built.

In general, the more modern your applications browser support is, the smaller the filesize as the code can rely on modern API's being present and not have to ship polyfills or shimmed code.

By default, applications generated from official Nx generators ship an aggressively modern browser support config, in the form of a `.browserlistrc` file in the root of the application with the following contents.

```
last 1 Chrome version
last 1 Firefox version
last 2 Edge major versions
last 2 Safari major version
last 2 iOS major versions
Firefox ESR
not IE 9-11 # For IE 9-11 support, remove 'not'.
```

This configuration is used for many tools including babel, autoprefixer, postcss, and more to decide which transforms are necessary on the source code when producing built code to run in the browser.

## Adding Support for IE 11

Adding support for IE or any other browser is as easy as changing the `.browserlistrc` file, following the rules and options listed on the [browserslist documentation](https://github.com/browserslist/browserslist#queries). These changes will affect differential loading and how the code is processed through babel and other tools for producing your builds.

To add support for IE 11 simply change the final line in the `.browserlistrc` file to include IE:

```
last 1 Chrome version
last 1 Firefox version
last 2 Edge major versions
last 2 Safari major version
last 2 iOS major versions
Firefox ESR
IE 11
```

For additional information regarding the format and rule options, please see: https://github.com/browserslist/browserslist#queries

## Debugging Browser Support

Sometimes broad configurations like `> 0.5%, not IE 11` can lead to surprising results, due to supporting browsers like Opera Mini or Android UC browser.

To see what browsers your configuration is supporting, run `npx browserslist` in application directory to get an output of browsers and versions to support.

```sh
$ npx browserslist
and_chr 61
chrome 83
edge 83
edge 81
firefox 78
firefox 68
ie 11
ios_saf 13.4-13.5
ios_saf 13.3
ios_saf 13.2
ios_saf 13.0-13.1
ios_saf 12.2-12.4
ios_saf 12.0-12.1
safari 13.1
safari 13
safari 12.1
safari 12
```

Alternatively, if your support config is short you can just add it as a string param on the CLI:

```sh
npx browserslist '> 0.5%, not IE 11'
```
