Jo is a JavaScript framework for mobile applications. It’s fully compatible with PhoneGap, which it relies on for creating native applications. It’s designed to be as lightweight as possible – its minified & gzipped JavaScript is just over 12KB with no dependencies. In addition to mobile Web apps and native apps, Jo can be used to build dashboard widgets.

Joe was built by Dave Balmer, a veteran Yahoo developer now working for HP on WebOS.

According to Ballmer’s JSConf presentation, the core principles of Jo are:

  • Don’t try to “fix” JavaScript
  • Let CSS3 do its job
  • Keep the code light

He says Jo also follows many of the principles from JavaScript: The Good Parts

  • Constructor nesting
  • Method chaining
  • Custom extend() method
  • Observer patterns
  • Supports either bind or this