How to Compress Javascript

First, you can try to make the javascript file smaller itself. There are lots of utilities to “crunch” your files by
removing whitespace and comments.

You can do this, but these tools can be finnicky and may make unwanted changes if your code isn’t formatted
properly. Here’s what you can do:

1. Run JSLint (online or downloadable version) to analyze your code and make sure it is well-formatted.

2. Use Rhino to compress your javascript. There are some online packers, but Rhino actually analyzes your source
code so it has a low chance of changing it as it compresses, and it is scriptable.

Install Rhino (it requires Java), then run it from the command-line:

java -jar custom_rhino.jar -c myfile.js > myfile.js.packed 2>&1
 
This compresses myfile.js and spits it out into myfile.js.packed. Rhino will remove spaces, comments and shorten
variable names where appropriate. The “2>&1″ part means “redirect standard error to the same location as the
output”, so you’ll see any error messages inside the packed file itself (cool, eh? Learn more here.).