Rand Stats



JS::Minify Build Status

JS::Minify removes comments and unnecessary whitespace from JavaScript files. It typically reduces filesize by half, resulting in faster downloads. This is a Perl 6 port of JSMin originally created by Douglas Crawford. JS::Minify incorporates several bug-fixes that have been resolved in various JSMin ports from other languages (Perl, Python, etc.).

JS::Minify is considered safe:


Minify a JavaScript file and have the output written directly to another file:

use JS::Minify;

my $js = slurp 'myScript.js';
spurt 'myScript.min.js', js-minify(input => $js);

Stream output via client consumer Channel:

my $js = slurp 'myScript.js';
my $stream = Channel.new;

js-minify(input => $js, stream => $stream);

my $out = open "myScript.min.js", :rw;
react {
  whenever $stream -> $chr {
    # Client supplied $stream is auto-closed
    # when minification has completed.

Minify a JavaScript string literal:

my $minified_javascript = js-minify(input => 'var x = 2;');

Include a copyright comment at the top of the minified code:

js-minify(input => 'var x = 2;', copyright => 'BSD License');

Treat ';;;' as '//' so that debugging code can be removed. This is a common JavaScript convention for minification:

js-minify(input => "var x = 2;\n;;;alert('hi');\nvar x = 2;", :strip_debug)
# output: 'var x=2;var x=2;'

The input parameter is mandatory. The copyright, strip_debug, and stream parameters are optional and can be used in any combination.


This module removes unnecessary whitespace from JavaScript code. The primary requirement developing this module is to not break working code: if working JavaScript is in input then working JavaScript is output. It is ok if the input has missing semi-colons, snips like '++ +' or '12 .toString()', for example. Internet Explorer conditional comments are copied to the output but the code inside these comments will not be minified.

The ECMAScript specifications allow for many different whitespace characters: space, horizontal tab, vertical tab, new line, carriage return, form feed, and paragraph separator. This module understands all of these as whitespace except for vertical tab and paragraph separator. These two types of whitespace are not minimized.

For static JavaScript files, it is recommended that you minify during the build stage of web deployment. If you minify on-the-fly then it might be a good idea to cache the minified file. Minifying static files on-the-fly repeatedly is wasteful.


Exported by default: js-minifiy()

See Also

JavaScript::Minifier (Perl)


You can obtain the latest source code and submit bug reports on the github repository for this module: https://github.com/scmorrison/JS-Minify.


JS::Minify is based on the Perl Javascript::Minifier module developed by the following:

The original JSMin was developed by Douglas Crockford:

License Information

"JS::Minify" is free software; you can redistribute it and/or modify it under the terms of the Artistic License 2.0. (Note that, unlike the Artistic License 1.0, version 2.0 is GPL compatible by itself, hence there is no benefit to having an Artistic 2.0 / GPL disjunction.) See the file LICENSE for details.