# eslint-plugin-escompat

This plugin will report eslint errors for code which - if left untranspiled - will not work in some browsers.

This is useful if you intend to ship code without first using a transpiler, such as [Babel](https://babeljs.io).

This _won't_ lint for features that can be polyfilled. For that you can use [eslint-plugin-compat][epc].

## Installation

```bash
npm install --save-dev eslint-plugin-escompat
```

Add `"escompat"` to `.eslintrc` `"plugins"` section, add `"browser": true` to `"env"`, then configure the individual `"escompat/*"` rules.

Alternatively, you can use the `recommended` configuration which will do this for you, with the `"escompat/*"` rules reporting errors (as in the snippet above).
```js
// .eslintrc
{
  "extends": ["plugin:escompat/recommended"]
}
```

### TypeScript Users

Aside from the `recommended` config, there are also multiple `typescript` configs which can be used if you're using TypeScript. The TypeScript configs only enable some of the rules, avoiding enabling rules for which `typescript` safely transpiles down to a more compatible syntax. Extend the typescript config that matches your `tsconfig.json` `target` value.

```js
// .eslintrc
{
  "extends": ["plugin:escompat/typescript-2016"]
}
```

## Targeting Browsers

`eslint-plugin-escompat` uses the `browserslist` configuration in `package.json`

If you have a browserlist, is is safe to enable all of these rules - as any
that do not coincide with your chosen browsers will be turned off
automatically.

See [browserslist/browserslist](https://github.com/browserslist/browserslist) for configuration. Here's some examples:

```js
// Simple configuration (package.json)
{
  // ...
  "browserslist": ["last 1 versions", "not ie <= 8"],
}
```

```js
// Use development and production configurations (package.json)
{
  // ...
  "browserslist": {
    "development": ["last 2 versions"],
    "production": ["last 4 versions"]
  }
}
```

:bulb: You can also define browsers in a [separate browserslist file](https://github.com/browserslist/browserslist#config-file)

## Rules

 - [no-async-generator](./docs/no-async-generator.md)
 - [no-async-iteration](./docs/no-async-iteration.md)
 - [no-bigint](./docs/no-bigint.md)
 - [no-bind-operator](./docs/no-bind-operator.md)
 - [no-computed-class-fields](./docs/no-computed-class-fields.md)
 - [no-do-expression](./docs/no-do-expression.md)
 - [no-dynamic-import](./docs/no-dynamic-import.md)
 - [no-edge-destructure-bug](./docs/no-edge-destructure-bug.md)
 - [no-exponentiation-operator](./docs/no-exponentiation-operator.md)
 - [no-nullish-coalescing](./docs/no-nullish-coalescing.md)
 - [no-numeric-separators](./docs/no-numeric-separators.md)
 - [no-object-rest-spread](./docs/no-object-rest-spread.md)
 - [no-optional-catch](./docs/no-optional-catch.md)
 - [no-optional-chaining](./docs/no-optional-chaining.md)
 - [no-pipeline-operator](./docs/no-pipeline-operator.md)
 - [no-private-class-fields](./docs/no-private-class-fields.md)
 - [no-public-instance-class-fields](./docs/no-public-instance-class-fields.md)
 - [no-public-static-class-fields](./docs/no-public-static-class-fields.md)
 - [no-regexp-lookbehind](./docs/no-regexp-lookbehind.md)
 - [no-regexp-named-groups](./docs/no-regexp-named-groups.md)
 - [no-regexp-s-flag](./docs/no-regexp-s-flag.md)

## Inspiration
This project was largely inspired by the great [eslint-plugin-compat][epc] library.

[epc]: https://github.com/amilajack/eslint-plugin-compat