I threw this up on npm a long time ago but there are better options now. Packer appears to be unsupported and has bugs like this that cause it to generate invalid JavaScript. I recommend using a community-supported JavaScript minifier such as uglify instead. I'm only keeping this page up on GitHub because some packages likely depend on this package and may attempt to navigate here.
This is a simple port of /packer/ by Dean Edwards to node.js.
If you use npm:
npm install packer
If you don't use npm, clone this repository or download the latest version using the GitHub repository Downloads link.
This module contains one function called pack(script, base62, shrink):
> var packer = require('packer');
> packer.pack('1 + 2');
'1+2'
> packer.pack('', true);
'eval(function(p,a,c,k,e,r){e=String;if(!\'\'.replace(/^/,String)){while(c--)r[c]=k[c]||c;k=[function(e){return r[e]}];e=function(){return\'\\\\w+\'};c=1};while(c--)if(k[c])p=p.replace(new RegExp(\'\\\\b\'+e(c)+\'\\\\b\',\'g\'),k[c]);return p}(\'\',2,0,\'\'.split(\'|\'),0,{}))'
It also adds the packer command:
$ packer -h
usage: <script> [options]
options:
-i FILE Input file (default stdin)
-o FILE Output file (default stdout)
-b Base62 encode
-s Shrink variables
$ echo 1 + a | packer -b
eval(function(p,a,c,k,e,r){e=String;if(!''.replace(/^/,String)){while(c--)r[c]=k[c]||c;k=[function(e){return r[e]}];e=function(){return'\\w+'};c=1};while(c--)if(k[c])p=p.replace(new RegExp('\\b'+e(c)+'\\b','g'),k[c]);return p}('1+0',2,2,'a|'.split('|'),0,{}))