Module: SourceMap::JSMin

Defined in:
lib/source_map/jsmin.rb

Overview

JSMin

Ruby implementation of Douglas Crockford’s JavaScript minifier, JSMin.

Author

Ryan Grove ([email protected])

Version

1.0.1 (2008-11-10)

Copyright

Copyright © 2008 Ryan Grove. All rights reserved.

Website

github.com/rgrove/jsmin

Example

require 'rubygems'
require 'jsmin'

File.open('example.js', 'r') {|file| puts JSMin.minify(file) }

Defined Under Namespace

Classes: ParseError

Constant Summary collapse

CHR_APOS = 
"'".freeze
CHR_ASTERISK = 
'*'.freeze
CHR_BACKSLASH = 
'\\'.freeze
CHR_CR = 
"\r".freeze
CHR_FRONTSLASH = 
'/'.freeze
CHR_LF = 
"\n".freeze
CHR_QUOTE = 
'"'.freeze
CHR_SPACE = 
' '.freeze
ORD_LF = 
?\n
ORD_SPACE = 
?\
ORD_TILDE = 
?~

Class Method Summary collapse

Class Method Details

.minify(input, opts = {}) ⇒ Object

Reads JavaScript from input (which can be a String or an IO object) and returns a String containing minified JS.

opts can contain :input_filename # an input filename to include in the sourcemap (required). :output_filename # an output filename to include in the sourcemap. :source_root # the sourceRoot to include in the sourcemap.

While the output_filename can be anything you like, in order for the source map to work correctly, the :source_root + :input_filename must map to a browser- accessible version of the input file.

If you set an absolute url as :input_filename, then you don’t need to set :source_root, but it’s nicer if you separate those concerns.

Once you have a source map object you’ll probably want to save it into files as in the example:

map = JSMin::SourceMap.minify(File.read("foo.js"),
                 :input_filename => 'foo.js',
                 :output_filename => 'foo.min.js',
                 :source_root => 'http://localhost:3000/javascripts/')

# output the generated, minified, javascript to foo.js.min
File.open('foo.min.js', 'w') { |f| f << map.generated_output }

# output the generated source map to foo.
File.open('foo.map.json', 'w') { |f| f << map.to_s }

Returns:

  • SourceMap



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# File 'lib/source_map/jsmin.rb', line 111

def minify(input, opts={})
  @js = StringScanner.new(input.is_a?(IO) ? input.read : input.to_s)
  @source = input.is_a?(IO) ? input.inspect : input.to_s[0..100]
  @line = 1
  @column = 0
  @file = opts[:input_filename] or raise ":input_filename is required"

  @a         = "\n"
  @b         = nil
  @lookahead = nil
  @source_map = SourceMap.new(:file => opts[:output_filename],
                             :source_root => opts[:source_root],
                             :generated_output => '')

  action_get

  while !@a.nil? do
    case @a
    when CHR_SPACE
      if alphanum?(@b)
        action_output
      else
        action_copy
      end

    when CHR_LF
      if @b == CHR_SPACE
        action_get
      elsif @b =~ /[{\[\(+-]/
        action_output
      else
        if alphanum?(@b)
          action_output
        else
          action_copy
        end
      end

    else
      if @b == CHR_SPACE
        if alphanum?(@a)
          action_output
        else
          action_get
        end
      elsif @b == CHR_LF
        if @a =~ /[}\]\)\\"+-]/
          action_output
        else
          if alphanum?(@a)
            action_output
          else
            action_get
          end
        end
      else
        action_output
      end
    end
  end

  @source_map
end

.raise(err) ⇒ Object 



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# File 'lib/source_map/jsmin.rb', line 76

def raise(err)
  super ParseError.new(err, @source, @line)
end