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https://github.com/nickserv/eslint-config-modern
ESLint configuration for modern JavaScript that improves code quality by removing bad features and preventing anti-patterns
https://github.com/nickserv/eslint-config-modern
Last synced: 23 days ago
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ESLint configuration for modern JavaScript that improves code quality by removing bad features and preventing anti-patterns
- Host: GitHub
- URL: https://github.com/nickserv/eslint-config-modern
- Owner: nickserv
- Created: 2018-07-28T13:56:45.000Z (over 6 years ago)
- Default Branch: main
- Last Pushed: 2023-07-18T22:57:25.000Z (over 1 year ago)
- Last Synced: 2024-09-17T00:18:23.641Z (about 2 months ago)
- Language: JavaScript
- Homepage:
- Size: 255 KB
- Stars: 1
- Watchers: 3
- Forks: 0
- Open Issues: 10
-
Metadata Files:
- Readme: README.md
Awesome Lists containing this project
README
# eslint-config-modern
ESLint configuration for modern JavaScript that improves code quality by removing bad features and preventing anti-patterns
## Installation
You can install ESLint using npm or Yarn:
```
npm install eslint --save-dev
```
```
yarn add eslint --dev
```
Then install this configuration:
```
npm install eslint-config-modern --save-dev
```
```
yarn add eslint-config-modern --dev
```
## Usage
In your `.eslintrc` file, add:
```json
"extends": "modern"
```
## Environment support
This config uses features from ES6/ES2015 to ES2019 which are supported in the following environments:
- Chrome
- Firefox
- Safari
- Node.js 12.17.0+
- TypeScript 2.7+
## Guidelines
### Consistently format code with Prettier
[Prettier](https://prettier.io/) is highly recommended to format your code. It is much more opinionated, powerful, and consistent than ESLint's formatting support. By using both, you can get better formatting from Prettier and still get advice of what features to use and potential errors in ESLint. Removing formatting from this style guide also makes it much simpler and more flexible, as you can use any settings you'd like in Prettier.
While configuration is not required, it's recommended you enable support for ES2017 trailing commas:
```json
"trailingComma": "all"
```
### Use new replacements of problematic features
JavaScript has many problematic and difficult to understand syntax features that have been replaced by newer features. Migrating to new features can drastically improve the readability, safety, and consistency of JavaScript.
- Use ES classes with `class` instead of constructor functions with `function`.
- Use ES modules instead of globals or `"use strict"`.
- Replace `var` with `const` if you don't need to reassign the variable, and `let` if you do.
- Replace `for (const i = 0; i < array.length; i++)` and `for (const value in array)` with `for (const value of array)`.
- Only use `` for string concatenation and + for addition.
- Use spread arguments like `...args` instead of `arguments`.
- Prefer Promises over callbacks when using async errors.
- Prefer `async`/`await` over `.then()` to use Promises.
- Don't give `parseInt()` a radix, it properly defaults to 10 on modern browsers.
- Don't assign `this` to a variable, use arrow functions or `.bind()` to avoid shadowing.
- Use `===` and `!==` instead of `==` and `!=`.
- Use `fetch` or a third party library to make requests in browsers instead of `XMLHTTPRequest`. `undici` is a good alternative for Node.
### Improve semantics
Some features have potentially dangerous or confusing usages and can be improved with care.
- Use `null` instead of `undefined`, unless you're comparing with an existing `undefined` value.
- Use break/return/throw for every `case` in `switch`.
- Don't extend or reassign built in types and values.
- Prefer standard APIs over third party packages when you can get equivalent functionality.
- Use capital letters for class names to signify that `new` should be used to create instances.
- Only throw Error objects (or subclasses).
### Avoid bad features
Some features are too dangerous or confusing to be worth using.
- Avoid `eval()`, use other techniques to make code dynamic.
- Avoid `continue`, use conditional statements inside blocks instead.
- Avoid typed wrappers (Boolean/Number/String/Object/Array), use literals like `false`, `0`, `''`, `{}`, and `[]` instead.
- Avoid `with`, manually read properties or use destructuring instead.
- Avoid `void`, it's better to use `undefined` or break up multiple statements instead.
- Avoid bitwise operators like `&` and `|`, they're usually confused with the `&&` and `||` (and/or) operators, and bitwise operations are not very performant or useful in JavaScript.
## Inspiration
- https://github.com/eslint/eslint/blob/master/conf/eslint-recommended.js
- https://github.com/prettier/prettier
- https://github.com/prettier/eslint-config-prettier
- https://standardjs.com/
- https://www.jslint.com/
- https://github.com/ssoloff/eslint-config-crockford
- https://github.com/airbnb/javascript
- https://github.com/facebook/create-react-app/tree/master/packages/eslint-config-react-app