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image-type

Detect the image type of an ArrayBuffer/Uint8Array

See the file-type module for more file types and a CLI.

Install

npm install image-type

Usage

Node.js
import {readChunk} from 'read-chunk';
import imageType, {minimumBytes} from 'image-type';

const buffer = await readChunk('unicorn.png', {length: minimumBytes});

await imageType(buffer);
//=> {ext: 'png', mime: 'image/png'}

Or from a remote location:

import https from 'node:https';
import imageType, {minimumBytes} from 'image-type';

const url = 'https://upload.wikimedia.org/wikipedia/en/a/a9/Example.jpg';

https.get(url, response => {
	response.on('readable', () => {
		(async () => {
			const chunk = response.read(minimumBytes);
			response.destroy();
			console.log(await imageType(chunk));
			//=> {ext: 'jpg', mime: 'image/jpeg'}
		})();
	});
});
Browser
const xhr = new XMLHttpRequest();
xhr.open('GET', 'unicorn.png');
xhr.responseType = 'arraybuffer';

xhr.onload = () => {
	(async () => {
		await imageType(new Uint8Array(this.response));
		//=> {ext: 'png', mime: 'image/png'}
	})();
};

xhr.send();

API

imageType(input)

Returns an Promise<object> with:

Or undefined when there is no match.

input

Type: ArrayBuffer | Uint8Array

It only needs the first minimumBytes amount of bytes.

minimumBytes

Type: number

The minimum amount of bytes needed to detect a file type. Currently, it's 4100 bytes, but it can change, so don't hardcode it.

Supported file types

SVG isn't included as it requires the whole file to be read, but you can get it here.

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