mime-detect

Detect mime type and encoding (aka Content-Type) from buffer, file content and filename.


Supported both node.js and browser.
(It can be bundled with esbuild.)

Powered by:

- file (Inspired by mimetype-magic)
- mime-db

Installation

``bash
npm i mime-detect
`

Alternatively, you can also install it pnpm or yarn for better DX.

Usage Example

`typescript
import { readdirSync, readFileSync } from 'fs'
import { join } from 'path'
import {
detectBufferMime,
detectFileMime,
detectFilenameMime,
} from 'mime-detect'

// return Promise if not given callback
console.log(await detectFileMime('image.jpg'))
// print 'image/jpeg'

// also support callback-style for less async overhead
detectFileMime('index.html', (error, mime) => console.log(mime))
// print 'text/html; charset=us-ascii'

// also can detect from in-memory binary data
let mime = await detectBufferMime(buffer)

// If the mime is text/plain or application/octet-stream, it can determine mime from filename. Otherwise, the original mime will be returned
mime = detectFilenameMime('users.csv', mime)
`

Typescript Signatures

`typescript
export function detectFileMime(file: string, cb: DetectMimeCallback): void
export function detectFileMime(file: string): Promise

export function detectFilenameMime(file: string, mime?: string): string

export function detectBufferMime(buffer: Buffer, cb: DetectMimeCallback): void
export function detectBufferMime(buffer: Buffer): Promise

export interface DetectMimeCallback {
(error: Error, mime?: string): void
(error: null, mime: string): void
}

/**
* @description return file extension name without dot
* e.g. "audio/mp4" -> "m4a"
* e.g. "video/x-matroska" -> "mkv"
*/
export function mimeToExt(mime: string): string
``

License

This project is licensed with BSD-2-Clause

This is free, libre, and open-source software. It comes down to four essential freedoms [[ref]](https://seirdy.one/2021/01/27/whatsapp-and-the-domestication-of-users.html#fnref:2):

- The freedom to run the program as you wish, for any purpose
- The freedom to study how the program works, and change it so it does your computing as you wish
- The freedom to redistribute copies so you can help others
- The freedom to distribute copies of your modified versions to others