Type '(filenames: string[]) => Commands | Promise<Commands>' is not assignable to type 'string'

[niebag]

Description

I believe my config should work. According to the documentation, I should be able to have an array of functions assigned to a matcher e.g. '*.{ts,tsx,cjs,js}'. It seems the current lint-staged types don't allow this.

lint-staged.config.js

import path from "path";

/** @type {import("lint-staged").ConfigFn} */
function lint(filenames) {
    if (filenames.length > 10) return 'next lint --fix';

    return `next lint --fix --file ${filenames.map((f) => path.relative(process.cwd(), f)).join(' --file ')}`;
}

/** @type {import("lint-staged").ConfigFn} */
function prettier(filenames) {
    if (filenames.length > 10) return 'prettier --write';

    return `prettier --write ${filenames.map((f) => path.relative(process.cwd(), f)).join(' ')}`;
}

/** @type {import("lint-staged").Config} */
const config = {
    '*.{ts,tsx,cjs,js}': [lint], // Type '(filenames: string[]) => Commands | Promise<Commands>' is not assignable to type 'string'
    // '*.{ts,tsx,cjs,js}': lint // This works
};

export default config;

index.d.ts

export type Commands = string[] | string;

export type ConfigFn = (filenames: string[]) => Commands | Promise<Commands>;

export type Config = ConfigFn | { [key: string]: Commands | ConfigFn };

As shown, this only allows a string, an array of strings or a single function in { [key: string]: Commands | ConfigFn }.

I think this could easily fixed by changing

export type Config = ConfigFn | { [key: string]: Commands | ConfigFn };

to

export type Config = ConfigFn | { [key: string]: Commands | ConfigFn | ConfigFn[] };

Steps to reproduce

1. bun add --dev lint-staged @types/lint-staged
2. Make file called lint-staged.config.js
3. Create a config as shown in this issue's Description

Environment

• OS: MacOS Sonoma 14.1
• Node.js: v18.18.0
• lint-staged: ^15.2.0
• @types/lint-staged: ^13.2.2

[iiroj]

The @types/lint-staged package is not officially supported, so I can't really comment on it.

[iiroj]

Closing in place of #1359