Minify CSS

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-contrib-cssmin --save-dev

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

grunt.loadNpmTasks('grunt-contrib-cssmin');

Issues with the output should be reported on the clean-css issue tracker.

Run this task with the grunt cssmin command.

Options are passed to clean-css. In addition this task defines some extra options:

Type: string
Choices: 'min', 'gzip'
Default: 'min'

Report minification result or both minification and gzip results. This is useful to see exactly how well clean-css is performing but using 'gzip' will make the task take 5-10x longer to complete. Example output.

Type: boolean
Choices: true, false
Default: false

Enable Source Maps.

cssmin: {
  options: {
    mergeIntoShorthands: false,
    roundingPrecision: -1
  },
  target: {
    files: {
      'output.css': ['foo.css', 'bar.css']
    }
  }
}

cssmin: {
  target: {
    files: [{
      expand: true,
      cwd: 'release/css',
      src: ['*.css', '!*.min.css'],
      dest: 'release/css',
      ext: '.min.css'
    }]
  }
}

• 2023-05-01   v5.0.0   Update dependencies. Drop Node.js < 14 support.
• 2021-02-15   v4.0.0   Update all dependencies including clean-css v5.x. Drop Node.js < 10 support.
• 2018-09-07   v3.0.0   Update all dependencies. Drop Node.js < 6 support.
• 2017-07-27   v2.2.1   Fix issue with relativeTo for clean-css v4.x.
• 2017-05-10   v2.2.0   Update clean-css to v4.1.1.
• 2017-04-17   v2.1.0   Set required Node.js version to >=4 since clean-css 4.x requires that.
• 2017-02-02   v2.0.0   Update clean-css to v4.0.3.
• 2016-08-31   v1.0.2   Fix issues for node 6.
• 2016-03-16   v1.0.1   Downgrade maxmin to support Node.js 0.10.
• 2016-03-04   v1.0.0   Updated docs. Point main to task and removed peerDeps. Update clean-css to v3.4.1.
• 2015-09-15   v0.14.0   Bump to cssmin ~3.4.0. Minor test fixes.
• 2015-07-27   v0.13.0   Bump to cssmin ~3.3.0.
• 2015-05-09   v0.12.3   Improve reporting of errors and warnings. Log out written files and the saved size. Fix absolute paths.
• 2015-02-20   v0.12.2   Set the rebase option to false by default.
• 2015-02-09   v0.12.0   Add sourceMap option.
• 2014-12-24   v0.11.0   Bump clean-css to 3.0.1. Remove banner option.
• 2014-06-11   v0.10.0   Update clean-css v2.2.0.
• 2014-02-01   v0.9.0   Refactor. Remove grunt-lib-contrib dependency. Backwards-compatibly remove false choice from report.
• 2014-02-14   v0.8.0   Update clean-css v2.1.0.
• 2013-11-23   v0.7.0   Update clean-css v2.0.0.
• 2013-09-14   v0.6.2   Support relative URLs via clean-css ~1.1.1.
• 2013-05-25   v0.6.1   Support import in-lining via clean-css ~1.0.4.
• 2013-04-05   v0.6.0   Update clean-css dependency to ~1.0.0.
• 2013-03-14   v0.5.0   Support for report option (false by default).
• 2013-03-10   v0.4.2   Add banner option. Support clean-css keepSpecialComments.
• 2013-02-17   v0.4.1   Update clean-css dependency to ~0.10.0.
• 2013-02-15   v0.4.0   First official release for Grunt 0.4.0.
• 2013-01-23   v0.4.0rc7   Updating grunt/gruntplugin dependencies to rc7. Changing in-development grunt/gruntplugin dependency versions from tilde version ranges to specific versions.
• 2013-01-09   v0.4.0rc5   Updating to work with grunt v0.4.0rc5. Switching to this.files API.
• 2012-11-01   v0.3.2   Update clean-css dep.
• 2012-10-12   v0.3.1   Rename grunt-contrib-lib dep to grunt-lib-contrib.
• 2012-09-23   v0.3.0   Options no longer accepted from global config key.
• 2012-09-10   v0.2.0   Refactored from grunt-contrib into individual repo.

Task submitted by Tim Branyen

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