UUID_v4.js

function uuid()
{
    var seed = Date.now();
    if (window.performance && typeof window.performance.now === "function") {
        seed += performance.now();
    }

    var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.replace(/[xy]/g, function (c) {
        var r = (seed + Math.random() * 16) % 16 | 0;
        seed = Math.floor(seed/16);

        return (c === 'x' ? r : r & (0x3|0x8)).toString(16);
    });

    return uuid;
}

// https://stackoverflow.com/questions/105034/create-guid-uuid-in-javascript
var uniqueId = Math.random().toString(36).substring(2) 
               + (new Date()).getTime().toString(36);

function generateGuid() {
  var result, i, j;
  result = '';
  for(j=0; j<32; j++) {
    if( j == 8 || j == 12 || j == 16 || j == 20) 
      result = result + '-';
    i = Math.floor(Math.random()*16).toString(16).toUpperCase();
    result = result + i;
  }
  return result;
}