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Parse CSS and add vendor-prefixed CSS properties using the Can I Use database. Based on Autoprefixer.

Deprecation notice

This project has been deprecated in favour of grunt-postcss.


Build Status Dependency Status Built with Grunt

Autoprefixer parses CSS and adds vendor-prefixed CSS properties using the Can I Use database.

Getting Started

This plugin requires Grunt ~0.4.0

If you haven't used Grunt before, be sure to check out the Getting Started guide, as it explains how to create a Gruntfile as well as install and use Grunt plugins. Once you're familiar with that process, you may install this plugin with this command:

npm install grunt-autoprefixer --save-dev

Once the plugin has been installed, it may be enabled inside your Gruntfile with this line of JavaScript:


The "autoprefixer" task


In your project's Gruntfile, add a section named autoprefixer to the data object passed into grunt.initConfig().

  autoprefixer: {
    options: {
      // Task-specific options go here. 
    your_target: {
      // Target-specific file lists and/or options go here. 



Type: Array Default value: an array with default browsers

You can specify browsers actual for your project using this option:

options: {
  browsers: ['last 2 versions', 'ie 8', 'ie 9']

Or using a global config file named browserslist at the root of your project:

# Browsers that we support
> 5% in US
Last 2 versions

Read more about browserslist here.


Type: Boolean Default value: true

Pass false to disable ‘cascade’ indentation. Read more here.


Type: Boolean Default value: true

Pass false to disable outdated prefixes cleaning. Read more here.


Type: Boolean|String Default value: false

Set it to true if you want to get an output patch file:

options: {
  diff: true // or 'custom/path/to/file.css.patch' 

Also you can specify a path where to save this file. More examples in Gruntfile.

Type: Boolean|Object Default value: false

If the map option isn't defined or is set to false, Autoprefixer will neither create nor update a sourcemap.

If true is specified, Autoprefixer will try to find a sourcemap from a previous compilation step using an annotation comment (e.g. from Sass) and create a new sourcemap based on the found one (or just create a new inlined sourcemap). The created sourcemap can be either a separate file or an inlined map depending on what the previous sourcemap was.

You can gain more control over sourcemap generation by setting an object to the map option:

  • prev (string or false): a path to a directory where a previous sourcemap is (e.g. path/). By default, Autoprefixer will try to find a previous sourcemap using a path from the annotation comment (or using the annotation comment itself if the map is inlined). You can also set this option to false to delete the previous sourcemap.
  • inline (boolean): whether a sourcemap will be inlined or not. By default, it will be the same as a previous sourcemap or inlined.
  • annotation (string): set this option to URL path you wish the annotation comment to be e.g. path/ (by default, Autoprefixer will save your sourcemap to a directory where you save CSS). This option requires inline to be false or undefined.
  • sourcesContent (boolean): whether original contents (e.g. Sass sources) will be included to a sourcemap. By default, Autoprefixer will add contents only for new sourcemaps or if a previous sourcemap has them.

Type: Boolean Default value: false

Enable or disable PostCSS safe mode.

options: {
  safe: true

Check out project's Gruntfile.js for more examples.

Updating prefixes database

$ npm update caniuse-db


In lieu of a formal styleguide, take care to maintain the existing coding style. Add unit tests for any new or changed functionality. Lint and test your code using Grunt.