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# Uglifier [](https://travis-ci.org/lautis/uglifier) [](https://gemnasium.com/lautis/uglifier)
Ruby wrapper for [UglifyJS](https://github.com/mishoo/UglifyJS2) JavaScript compressor.
## Installation
Uglifier is available as a ruby gem.
$ gem install uglifier
Ensure that your environment has a JavaScript interpreter supported by
[ExecJS](https://github.com/sstephenson/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.
## Usage
```ruby
require 'uglifier'
Uglifier.new.compile(File.read("source.js"))
# => js file minified
# Or alternatively
Uglifier.compile(File.read("source.js"))
```
Uglifier also supports generating source maps:
```ruby
uglified, source_map = Uglifier.new.compile_with_map(source)
```
When initializing UglifyJS, you can tune the behavior of UglifyJS by passing options. For example, if you want disable variable name mangling:
```ruby
Uglifier.new(:mangle => false).compile(source)
# Or
Uglifier.compile(source, :mangle => false)
```
Available options and their defaults are
```ruby
{
:output => {
:ascii_only => true, # 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
:keep_fargs => false # Preserve unused function arguments
}, # 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
}
```
## Development
Tests are run using
bundle exec rake
See [CONTRIBUTING](https://github.com/lautis/uglifier/blob/master/CONTRIBUTING.md) for details about working on and contributing to Uglifier.
## Copyright
© Ville Lautanala. Released under MIT license, see [LICENSE](https://github.com/lautis/uglifier/blob/master/LICENSE.txt) for details.
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