eslint-plugin-typescript-compat ![Actions Status: test](https://github.com/azu/eslint-plugin-typescript-compat/actions?query=workflow%3A"test")

ESLint rule for browser compatibility of your TypeScript code.

- Lints the compatibilities between ECMAScript API.
- [ ] DOM API is not support yet
- Refers mdn-browser-compat-data, TypeScript Compiler API, and browserslist.
- Inspired by eslint-plugin-compat and eslint-plugin-typescript-compat-dom
- eslint-plugin-compat aims to JavaScript, while this plugin aims to TypeScript.
- eslint-plugin-es and eslint-plugin-es-x disallow to use ECMAScript syntax, but it does not support method like Array.prototype.includes

Supports

- [ ] JavaScript Built-in Object
- [x] Prototype method like Array.prototype.find
- [x] Static method like Array.from
- [ ] Object like Promise
- [ ] DOM API

Installation

$3

You need to install TypeScript and @typescript-eslint/parser

``
$ npm install eslint-plugin-typescript-compat typescript @typescript-eslint/parser --save-dev
`

$3

.eslintrc.json:

`diff
{
+ "extends": ["plugin:typescript-compat/recommended"],
+ "env": {
+ "browser": true
+ },
+ "parserOptions": {
+ "project": "./tsconfig.json"
+ },
// ...
}
`

Require parserOptions.project setting for using type information.

Also, your tsconfig.json should define lib that you want to detect.
The default value of TypeScript's lib is ES2015(ES6). So, TypeScript checker does not recognize ES2016+ features by default.

> Note: If --lib is not specified a default list of libraries are injected. The default libraries injected are:
>
> ► For --target ES5: DOM,ES5,ScriptHost
>
> ► For --target ES6: DOM,ES6,DOM.Iterable,ScriptHost
>
> -- https://www.typescriptlang.org/docs/handbook/compiler-options.html

:memo: Internally note. TypeScript Checker return intrinsicName: 'error', or intrinsicName: 'unknown' for non-recognized type.

If you want to detect ES2016+ features like Array.prototype.flag, you need to set "lib": ["ESNext"]

`json5
{
"compilerOptions": {
// ...
"lib": [
"ESNext",
"DOM"
]
}
}

`

$3

Browser targets are configured using browserslist.

You can configure browser targets in your package.json.

For example, Your project need to support IE 11.

`diff
{
// ...
+ "browserslist": [
+ "ie 11"
+ ]
}
`

For more details, see browserslist.

Example

When your browserlist configuration is:

`json5
"browserslist": [
"ie 11"
]
`

Following code includes Array.prototype.includes

`
const items = [1,2,3];
items.includes(2);
`

This rule show following error.

> Array.included is not supported in ie 11. https://developer.mozilla.org/docs/Web/JavaScript/Reference/Global_Objects/Array/find"

Options

$3

Add polyfills to the settings section of your eslint config.


`jso5
{
// ...
"settings": {
"polyfills": [
// Example of instance method, must add .prototype.
"Array.prototype.find"
]
}
}
``

LICENCE

MIT © azu

This ESLint plugin is based on these.

- TypeScript Compiler APIとmdn-browser-compat-dataとbrowserslistを使ってサポートされていない呼び出しを見つける - hitode909の日記
- hitode909/eslint-plugin-typescript-compat-dom: Uses mdn-browser-compat-data, browserslist, TypeScript Compiler API and lints compatibilities between browsers DOM APIs.