eslint-config-async

A shareable ESLint config for writing better asynchronous code.

Find an overview of what rules are enabled, and why, in this article:

📚 14 Linting Rules To Help You Write Asynchronous Code in JavaScript

Table of contents

- Table of contents
- Requirements
- Installation \& usage
- Non-TypeScript users
- TypeScript users
- Migrating from v2 to v3
- Migrating from v1 to v2

Requirements

- ESLint v9
- Node.js ^18.18.0, ^20.9.0, or >=21.1.0 (set by ESLint v9)

If you're using ESLint v8, you should use v2 of this library. Installation & usage for eslint-config-async v2.

Installation & usage

$3

Install this package and ESLint:

``shell
npm install --save-dev eslint eslint-config-async
`

In your eslint.config.js configuration file:

`js
const asyncConfig = require("eslint-config-async");

module.exports = [
...asyncConfig.base, // enable base rules
...asyncConfig.node, // enable Node.js specific rules (recommended)
];
`

$3

Install this package and its peer dependencies:

`shell
npm install --save-dev eslint eslint-config-async typescript typescript-eslint
`

In your eslint.config.js configuration file:

`js
const tseslint = require("typescript-eslint");
const asyncConfig = require("eslint-config-async");

module.exports = [
// One of tseslint configs must be enabled
// Either the base config
tseslint.configs.base, // adds the parser only, without any rules
// or
...tseslint.configs.recommended, // includes base + a list of recommended rules
// ..and others

...asyncConfig.base, // enable base rules
...asyncConfig.node, // enable Node.js specific rules (recommended)
...asyncConfig.typescript, // enable TypeScript specific rules
{
files: ["*.ts"], // tell ESLint to include TypeScript files
languageOptions: {
parserOptions: {
projectService: true,
tsconfigRootDir: __dirname,
},
},
},
];
`

Migrating from v2 to v3

Version 3 upgrades ESLint to v9. ESLint uses a flat configuration file. .eslintrc.* has been deprecated and you should rename it to eslint.config.js (or .cjs, .mjs):

`diff
- .eslintrc
+ eslint.config.js
`

In your eslint.config.js file, make the following changes:

`diff
- module.exports = {
- plugins: [
- 'eslint-plugin-node'
- ],
- extends: [
- 'async',
- 'async/node'
- ],
- };
+ const asyncConfig = require("eslint-config-async");
+
+ module.exports = [
+ ...asyncConfig.base, // enable base rules
+ ...asyncConfig.node, // enable Node.js specific rules (recommended)
+ ];
`

eslint-plugin-node is no longer maintained and has been replaced with its fork, eslint-plugin-n. eslint-plugin-n is not a peer dependency and is included with this library, therefore you no longer need to install it separately:

`shell
npm remove --save-dev eslint-plugin-node
`

For TypeScript users, change the contents of eslint.config.js file as follows:

`diff
- module.exports = {
- plugins: [
- 'eslint-plugin-node',
- '@typescript-eslint'
- ],
- extends: [
- 'async',
- 'async/node',
- 'async/typescript'
- ],
- parser: '@typescript-eslint/parser',
- parserOptions: {
- tsconfigRootDir: __dirname,
- project: ['./tsconfig.json'],
- }
- };

+ const tseslint = require("typescript-eslint");
+ const asyncConfig = require("eslint-config-async");
+
+ module.exports = [
+ tseslint.configs.base,
+ ...asyncConfig.base, // enable base rules
+ ...asyncConfig.node, // enable Node.js specific rules (recommended)
+ ...asyncConfig.typescript, // enable TypeScript specific rules
+ {
+ files: ["*.ts"], // tell ESLint to include TypeScript files
+ languageOptions: {
+ parserOptions: {
+ projectService: true,
+ tsconfigRootDir: __dirname,
+ },
+ },
+ },
+ ];
`

Replace @typescript-eslint/parser and @typescript-eslint/eslint-plugin with typescript-eslint:

`shell
npm remove @typescript-eslint/parser @typescript-eslint/eslint-plugin && npm install --save-dev typescript-eslint
`

Migrating from v1 to v2

Version 2 adds TypeScript specific rules and exports multiple configs, namely:

- Base rules (eslint-config-async)
- Node.js specific rules (eslint-config-async/node)
- TypeScript rules (eslint-config-async/typescript)

In version 1, the base and Node.js specific rules were included by default. In version 2, you need to explicitly add the Node.js rules:

`diff
module.exports = {
extends: [
- 'eslint-config-async'
+ 'eslint-config-async',
+ 'eslint-config-async/node'
],
}
`

Or using the short syntax:

`diff
module.exports = {
extends: [
- 'eslint-config-async'
+ 'async',
+ 'async/node'
],
}
`

If you added the TypeScript specific rules manually in your project, you can remove them and replace them with this config:

`diff
module.exports = {
extends: [
'async',
'async/node',
+ 'async/typescript'
],
rules: {
- "@typescript-eslint/await-thenable": "error",
- "@typescript-eslint/no-floating-promises": "error",
- "@typescript-eslint/no-misused-promises": "error",
- "@typescript-eslint/promise-function-async": "error",
}
}
``