gif-info is currently only available as a CommonJS module to use with Browserify.

npm install gif-info

A JavaScript library for reading information from animated GIFs

First you need to get the gif file into memory as ArrayBuffer. This is out of scope of gif-info, but you could for example load it via xhr with responseType set to arraybuffer. Then simply pass the data to the function exported by gif-info.

var xhr = require('xhr');
var gifInfo = require('gif-info');

var options = {
  url: 'fail.gif',
  method: 'GET',
  responseType: 'arraybuffer'
};

xhr(options, function(err, response, buffer) {
  var info = gifInfo(buffer);

  //Now use stuff like info.animated, info.duration or info.width.
});

• valid (bool) - Determines if the GIF is valid.
• animated (bool) - Determines if the GIF is animated.
• globalPalette (bool) - Determines if the GIF has a global color palette.
• globalPaletteSize (int) - Size of the global color palette.
• height (int) - Canvas height.
• width (int) - Canvas width.
• loopCount (int) - Total number of times the GIF will loop. 0 represents infitine.
• images ([images]) - Array of images contained in the GIF.
• isBrowserDuration (bool) - If any of the delay times are lower than the minimum value, this value will be set to true.
• duration (int) - Actual duration calculated from the delay time for each image. If isBrowserDuration is false, you should use this value.
• durationIE (int) - Duration for Internet Explorer (16fps)
• durationSafari (int) - Duration for Safari in milliseconds (50fps)
• durationFirefox (int) - Duration for Firefox in milliseconds (50fps)
• durationChrome (int) - Duration for Chrome in milliseconds (50fps)
• durationOpera (int) - Duration for Opera in milliseconds (50fps)

• identifier (string) - Image identifier (frame number or embeded string).
• top (int) - Image top position (Y).
• left (int) - Image left position (X).
• height (int) - Image height.
• width (int) - Image width.
• localPalette (bool) - Image has a local color palette.
• localPaletteSize (int) - Size of the local color palette.
• interlace (bool) - Image is/is not interlaced.
• delay (int) - Delay time in milliseconds.
• text (string) - frame text. aka Plain Text Extension.
• comments ([comments]) - Array of comment strings.
• disposal (int) - Disposal method. (0-7). See this for more details.

{
  "valid": true,
  "globalPalette": true,
  "globalPaletteSize": 256,
  "loopCount": 0,
  "height": 1610,
  "width": 899,
  "animated": true,
  "images": [
    {
      "identifier": "0",
      "localPalette": false,
      "localPaletteSize": 0,
      "interlace": false,
      "comments": [],
      "text": "",
      "left": 0,
      "top": 0,
      "width": 1610,
      "height": 899,
      "delay": 350,
      "disposal": 0
    },
    {
      "identifier": "1",
      "localPalette": true,
      "localPaletteSize": 256,
      "interlace": false,
      "comments": [],
      "text": "",
      "left": 0,
      "top": 0,
      "width": 1610,
      "height": 899,
      "delay": 350,
      "disposal": 0
    },
    {
      "identifier": "2",
      "localPalette": true,
      "localPaletteSize": 256,
      "interlace": false,
      "comments": [],
      "text": "",
      "left": 0,
      "top": 0,
      "width": 1610,
      "height": 899,
      "delay": 350,
      "disposal": 0
    },
    {
      "identifier": "3",
      "localPalette": true,
      "localPaletteSize": 256,
      "interlace": false,
      "comments": [],
      "text": "",
      "left": 0,
      "top": 0,
      "width": 1610,
      "height": 899,
      "delay": 350,
      "disposal": 0
    }
  ],
  "isBrowserDuration": false,
  "duration": 2800,
  "durationIE": 2800,
  "durationSafari": 2800,
  "durationFirefox": 2800,
  "durationChrome": 2800,
  "durationOpera": 2800
}

• What's In A GIF - Bit by Byte - Hands down the best write up on GIFs I've found.
• GIF98 - GIF98 RFC.
• Animated GIF Frame Rate by Browser - An awesome breakdown of how each browser renders animated GIFs. Thanks to Jeremiah Johnson for doing the hard work.
• GIF Format - GIF blocks.
• Hexfiend - Awesome open source HEX editor (OSX)

Licence: Do What The Fuck You Want To Public License

• Fixed width/height being switched.