Javascript compressors or packers are tools that compress the javascript file saving bandwidth. There are several tools that can do this. We will try to show some of them.
For tests I used Mootools v1.11 downloaded full with no compression.
Javascript Compressor

Highest compression level is with “high ascii” setting, “fast decode” unchecked and obtained a 0.224 compression. It uses Dean Edwards algorithm.
Creativyst® CSS & JavaScript Compressor (v2.2c)

This script runs in your browser. Obtained a 51.1% level of compression.
ShrinkSafe

This will ask you to upload the js script and will return a compressed version.
0.39 level.
JS Minifier

Set on agressive mode, will compress the test file to 40.4%.
jscrush – Online JavaScript compressor

jscrush makes use of Andrea Giammarchi’s JavaScript Compressor class and Er. Rochak Chauhan’s Create ZIP File class.
We had a 41.9 level of compression. This script is able to pack pack and combine more scripts in one file, so it saves the number of connections between browser and server.
Bananascript.com

This seems to be the winner.
cause it compress the file with 83.3%.
You have to set the charset to “ISO-8859-1″ or your script will not work.
Let us know if we missed some tools.
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2 Responses
Yep,
You’ve missed one: YUI compressor (a part of YUI library).
I haven’t heard about Bananascript.com – it looks sweet.
An alternative with better compression than Packer or JSNin
is Javascript Utility V2 at http://jsutility.pjoneil.net.
You might want to include this compactor/compressor in your analysis.
Regards
Pat