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

1npm i mime-detect

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

Usage Example

1import { readdirSync, readFileSync } from 'fs'
2import { join } from 'path'
3import {
4  detectBufferMime,
5  detectFileMime,
6  detectFilenameMime,
7} from 'mime-detect'
8
9// return Promise<string> if not given callback
10console.log(await detectFileMime('image.jpg'))
11// print 'image/jpeg'
12
13// also support callback-style for less async overhead
14detectFileMime('index.html', (error, mime) => console.log(mime))
15// print 'text/html; charset=us-ascii'
16
17// also can detect from in-memory binary data
18let mime = await detectBufferMime(buffer)
19
20// If the mime is text/plain or application/octet-stream, it can determine mime from filename. Otherwise, the original mime will be returned
21mime = detectFilenameMime('users.csv', mime)

Typescript Signatures

1export function detectFileMime(file: string, cb: DetectMimeCallback): void
2export function detectFileMime(file: string): Promise<string>
3
4export function detectFilenameMime(file: string, mime?: string): string
5
6export function detectBufferMime(buffer: Buffer, cb: DetectMimeCallback): void
7export function detectBufferMime(buffer: Buffer): Promise<string>
8
9export interface DetectMimeCallback {
10  (error: Error, mime?: string): void
11  (error: null, mime: string): void
12}
13
14/**
15 * @description return file extension name without dot
16 * e.g. "audio/mp4" -> "m4a"
17 * e.g. "video/x-matroska" -> "mkv"
18 */
19export 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]:

• 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