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is-jpg's Introduction

is-jpg

Check if a Buffer/Uint8Array is a JPEG image

Install

npm install is-jpg

Usage

Node.js
import {readChunk} from 'read-chunk';
import isJpg from 'is-jpg';

const buffer = await readChunk('unicorn.jpg', {length: 3});

isJpg(buffer);
//=> true
Browser
const xhr = new XMLHttpRequest();
xhr.open('GET', 'unicorn.jpg');
xhr.responseType = 'arraybuffer';

xhr.onload = () => {
	isJpg(new Uint8Array(this.response));
	//=> true
};

xhr.send();

API

isJpg(buffer)

Accepts a Buffer (Node.js) or Uint8Array.

It only needs the first 3 bytes.

Related

  • file-type - Detect the file type of a Buffer/Uint8Array

is-jpg's People

Contributors

richienb avatar sindresorhus avatar

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is-jpg's Issues

The package uploaded to npm is not licensed

The npm distribution of this package is not properly licensed. It does not contain full license text, which is an issue - see babel/babel#7308 (comment)

Effectively, this way the source code distributed on npm is unlicensed and cannot be used by anyone else (or, to be more precise, by anyone who cares about licensing).

  • license field in package.json: MIT
  • GitHub repository license file: license
  • npm package contents license: (missing) โš ๏ธ

To reproduce this issue:

$ mkdir /tmp/foobar
$ cd /tmp/foobar
$ npm install is-jpg
$ ls -al ./node_modules/is-jpg/  # look for a license file

Related issue: sindresorhus/ama#537

Image not passing

I was playing around with an app using this module, and noticed one of my jpeg images was failing.

Here's the image: (this is awkward)

hmm

I put some console.logs in your code:

if (!buf || buf.length < 4) {
    return false;
}

console.log(buf[0]);
console.log(buf[1]);
console.log(buf[2]);
console.log(buf[3]);

return buf[0] === 255 &&
    buf[1] === 216 &&
    buf[2] === 255 &&
    (buf[3] === 224 || buf[3] === 225);

and got this:

255
216
255
219

Any ideas? Thanks!

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