Ruby wrapper for UglifyJS JavaScript compressor.
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Uglifier Build Status Dependency Status

Ruby wrapper for UglifyJS JavaScript compressor.


Uglifier is available as ruby gem.

$ gem install uglifier

Ensure that your environment has a JavaScript interpreter supported by ExecJS. Usually, installing therubyracer gem is the best alternative.


require 'uglifier'"source.js"))
# => js file minified

# Or alternatively

When initializing UglifyJS, you can tune the behavior of UglifyJS by passing options. For example, if you want top-level variable names to be mangled: => true).compile(source)

# Or
Uglifier.compile(source, :toplevel => true)

Available options and their defaults are

  :mangle => true, # Mangle variable and function names, use :variables to skip function mangling
  :toplevel => false, # Mangle top-level variable names
  :except => [], # Variable names to be excluded from mangling
  :max_line_length => 32 * 1024, # Maximum line length
  :squeeze => true, # Squeeze code resulting in smaller, but less-readable code
  :seqs => true, # Reduce consecutive statements in blocks into single statement
  :dead_code => true, # Remove dead code (e.g. after return)
  :lift_vars => false, # Lift all var declarations at the start of the scope
  :unsafe => false, # Optimizations known to be unsafe in some situations
  :copyright => true, # Show copyright message
  :ascii_only => false, # Encode non-ASCII characters as Unicode code points
  :inline_script => false, # Escape </script
  :quote_keys => false, # Quote keys in object literals
  :beautify => false, # Ouput indented code
  :beautify_options => {
    :indent_level => 4,
    :indent_start => 0,
    :space_colon => false


Uglifier uses stitch to compile UglifyJs for non-node JS runtimes. If you need to update or patch UglifyJS, you can stitch UglifyJS using

node build.js

Submitting an issue

Uglifier uses the GitHub issue tracker to track bugs and features. Before submitting a bug report or feature request, check to make sure it hasn't already been submitted. You can indicate support for an existing issuse by voting it up. When submitting a bug report, please include a Gist that includes a stack trace and any details that may be necessary to reproduce the bug, including your gem version, Ruby version, MultiJSON engine and ExecJS runtime. Ideally, a bug report should include a pull request with failing specs.

Contributing to uglifier

  • Check out the latest master to make sure the feature hasn't been implemented or the bug hasn't been fixed yet
  • Check out the issue tracker to make sure someone already hasn't requested it and/or contributed it
  • Fork the project
  • Start a feature/bugfix branch
  • Commit and push until you are happy with your contribution
  • Make sure to add tests for it. This is important so I don't break it in a future version unintentionally.
  • Please try not to mess with the Rakefile, version, or history. If you want to have your own version, or is otherwise necessary, that is fine, but please isolate to its own commit so I can cherry-pick around it.


© Ville Lautanala, Flowdock. Released under MIT license, see LICENSE.txt for more details.