To minify scripts I use the online YUI compressor available here. Unfortunately though, from time to time the compressor throws errors that I cannot understand, especially since the script doesn't crash when being run.
e.g.:
[ERROR] 27:39:missing formal parameter
[ERROR] 27:39:missing } after function body
[ERROR] 31:13:identifier is a reserved word
[ERROR] 32:8:syntax error
By the way, the script I was just trying to minify is on http://picselbocs.com/plugins/digitize/digitize.js