Skip to content


Subversion checkout URL

You can clone with
Download ZIP
Ruby wrapper for UglifyJS JavaScript compressor.
JavaScript Ruby
Pull request Compare This branch is 1 commit ahead, 106 commits behind lautis:master.

Fetching latest commit…

Cannot retrieve the latest commit at this time

Failed to load latest commit information.

Uglifier Build Status Dependency Status

Ruby wrapper for UglifyJS JavaScript compressor.


Uglifier is available as a ruby gem.

$ gem install uglifier

Ensure that your environment has a JavaScript interpreter supported by ExecJS. Using therubyracer gem is a safe choice if a runtime isn't already present. Note that while JScript built-in Windows 7 and older works, it is extremely slow.


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

# Or alternatively

Uglifier also supports generating source maps:

uglified, source_map =

When initializing UglifyJS, you can tune the behavior of UglifyJS by passing options. For example, if you want disable variable name mangling: => false).compile(source)

# Or
Uglifier.compile(source, :mangle => false)

Available options and their defaults are

  :output => {
    :ascii_only => false,       # Escape non-ASCII characters
    :comments => :copyright,    # Preserve comments (:all, :jsdoc, :copyright, :none)
    :inline_script => false,    # Escape occurrences of </script in strings
    :quote_keys => false,       # Quote keys in object literals
    :max_line_len => 32 * 1024, # Maximum line length in minified code
    :bracketize => false,       # Bracketize if, for, do, while or with statements, even if their body is a single statement
    :semicolons => true,        # Separate statements with semicolons
    :preserve_line => false,    # Preserve line numbers in outputs
    :beautify => false,         # Beautify output
    :indent_level => 4,         # Indent level in spaces
    :indent_start => 0,         # Starting indent level
    :space_colon => false,      # Insert space before colons (only with beautifier)
    :width => 80,               # Specify line width when beautifier is used (only with beautifier)
    :preamble => nil            # Preamble for the generated JS file. Can be used to insert any code or comment.
  :mangle => {
    :eval => false,             # Mangle names when eval of when is used in scope
    :except => ["$super"],      # Argument names to be excluded from mangling
    :sort => false,             # Assign shorter names to most frequently used variables. Often results in bigger output after gzip.
    :toplevel => false          # Mangle names declared in the toplevel scope
  },                            # Mangle variable and function names, set to false to skip mangling
  :compress => {
    :sequences => true,         # Allow statements to be joined by commas
    :properties => true,        # Rewrite property access using the dot notation
    :dead_code => true,         # Remove unreachable code
    :drop_debugger => true,     # Remove debugger; statements
    :unsafe => false,           # Apply "unsafe" transformations
    :conditionals => true,      # Optimize for if-s and conditional expressions
    :comparisons => true,       # Apply binary node optimizations for comparisons
    :evaluate => true,          # Attempt to evaluate constant expressions
    :booleans => true,          # Various optimizations to boolean contexts
    :loops => true,             # Optimize loops when condition can be statically determined
    :unused => true,            # Drop unreferenced functions and variables
    :hoist_funs => true,        # Hoist function declarations
    :hoist_vars => false,       # Hoist var declarations
    :if_return => true,         # Optimizations for if/return and if/continue
    :join_vars => true,         # Join consecutive var statements
    :cascade => true,           # Cascade sequences
    :negate_iife => true,       # Negate immediately invoked function expressions to avoid extra parens
    :pure_getters => false,     # Assume that object property access does not have any side-effects
    :pure_funcs => nil,         # List of functions without side-effects. Can safely discard function calls when the result value is not used
    :drop_console => false,     # Drop calls to console.* functions
    :angular => false           # Process @ngInject annotations
  },                            # Apply transformations to code, set to false to skip
  :define => {},                # Define values for symbol replacement
  :enclose => false,            # Enclose in output function wrapper, define replacements as key-value pairs
  :source_filename => nil,      # The filename of the input file
  :source_root => nil,          # The URL of the directory which contains :source_filename
  :output_filename => nil,      # The filename or URL where the minified output can be found
  :input_source_map => nil,     # The contents of the source map describing the input
  :screw_ie8 => false           # Don't bother to generate safe code for IE8


Uglifier bundles its javascript dependencies using git submodules. If you want to rebuild the javascript you will first need to get the latest version of the code with git submodule update --init. After you have the git submodules at the desired versions, run rake js to recreate lib/uglify.js.

See CONTRIBUTING for details about contributing to Uglifier.


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

Something went wrong with that request. Please try again.