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   1 # is-jpg [![Build Status](https://travis-ci.org/sindresorhus/is-jpg.svg?branch=master)](https://travis-ci.org/sindresorhus/is-jpg)
   2
   3 > Check if a Buffer/Uint8Array is a [JPEG](http://en.wikipedia.org/wiki/JPEG) image
   4
   5 Used by [image-type](https://github.com/sindresorhus/image-type).
   6
   7
   8 ## Install
   9
  10 ```sh
  11 $ npm install --save is-jpg
  12 ```
  13
  14
  15 ## Usage
  16
  17 ##### Node.js
  18
  19 ```js
  20 var readChunk = require('read-chunk'); // npm install read-chunk
  21 var isJpg = require('is-jpg');
  22 var buffer = readChunk.sync('unicorn.jpg', 0, 3);
  23
  24 isJpg(buffer);
  25 //=> true
  26 ```
  27
  28 ##### Browser
  29
  30 ```js
  31 var xhr = new XMLHttpRequest();
  32 xhr.open('GET', 'unicorn.jpg');
  33 xhr.responseType = 'arraybuffer';
  34
  35 xhr.onload = function () {
  36         isJpg(new Uint8Array(this.response));
  37         //=> true
  38 };
  39
  40 xhr.send();
  41 ```
  42
  43
  44 ## API
  45
  46 ### isJpg(buffer)
  47
  48 Accepts a Buffer (Node.js) or Uint8Array.
  49
  50 It only needs the first 3 bytes.
  51
  52
  53 ## License
  54
  55 MIT © [Sindre Sorhus](http://sindresorhus.com)