gen-uuid.js

function generateUUID(){
  var d = new Date().getTime(),
      pattern = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'

  return pattern.replace(/[xy]/g, function(c) {
    var r = (d + Math.random()*16)%16 | 0
    d = Math.floor(d/16)
    return (c=='x' ? r : (r&0x3|0x8)).toString(16)
  })
}