image-type

2019-05-14 admin

image-type是什么

什么是image-type,Detect the image type of a Buffer/Uint8Array

image-type使用教程帮助文档

image-type Build Status

Detect the image type of a Buffer/Uint8Array

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

Install

$ npm install image-type

Usage

Node.js
const readChunk = require('read-chunk');
const imageType = require('image-type');

const buffer = readChunk.sync('unicorn.png', 0, 12);

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

Or from a remote location:

const http = require('http');
const imageType = require('image-type');

const url = 'https://assets-cdn.github.com/images/spinners/octocat-spinner-32.gif';

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

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

xhr.send();

API

imageType(input)

Returns an Object with:

  • ext - One of the supported file types
  • mime - The MIME type

Or null when there is no match.

input

Type: Buffer | Uint8Array

It only needs the first .minimumBytes bytes.

imageType.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.

License

MIT © Sindre Sorhus

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