UUID Generator

http://stackoverflow.com/questions/105034/how-to-create-a-guid-uuid-in-javascript

by Morgan Gilroy

HTML

<H1>Two methods to generate random UUIDv4</H1>
<br/> Psudo random string using Math.random() for all digits apart from the UUIDv4 version bits.<br/>
<br/>
<input id="generateUUID1" type="button" value="Generate UUID 1" /> <span id="uuid1"></span>
<br/><br/><br/> Hexadecimal timestamp for the first 11 digits then random string using window.crypto with failover to sudo random Math.random() for all remaining digits apart from the UUIDv4 version bits.<br/>
<br/>
<input id="generateUUID2" type="button" value="Generate UUID 2" /> <span id="uuid2"></span>

CSS

body {
  margin: 20px;
  font-family: Verdana, Geneva, sans-serif;
}

h1 {
  font-size: 2em;
  font-weight: bold;
}

span {
  font-family: "Courier New", Courier, monospace;
  font-weight: bold;
}

JavaScript

function generateUUID1() {
  var d = new Date().getTime();
  var uuid = 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'.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);
  });
  return uuid.toUpperCase();
}

document.getElementById('generateUUID1').onclick = function() {
  document.getElementById('uuid1').innerHTML = generateUUID1();
};
document.getElementById('uuid1').innerHTML = generateUUID1();



function generateUUID2() {
  var cryptoObj = window.crypto || window.msCrypto;
  var randomArray = new Uint8Array(20);
  if (cryptoObj != undefined && "getRandomValues" in cryptoObj) {
    crypto.getRandomValues(randomArray);
    randomArray.forEach(function(value, index) {
      randomArray[index] = value % 16 | 0
    });
  } else {
    randomArray.forEach(function(value, index) {
      randomArray[index] = Math.floor((Math.random() * 16) % 16 | 0)
    });
  }
  var timeStamp = new Date().getTime().toString(16).substr(-11);
  var i = 0;
  var uuid = (timeStamp.substr(0, 8) + "-" + timeStamp.substr(8) + 'x-4xxx-yxxx-xxxxxxxxxxxx').replace(/[xy]/g, function(c) {
    var r = randomArray[i++];
    return (c == 'x' ? r : (r & 0x3 | 0x8)).toString(16);
  });
  return uuid.toUpperCase();
}

document.getElementById('generateUUID2').onclick = function() {
  document.getElementById('uuid2').innerHTML = generateUUID2();
};
document.getElementById('uuid2').innerHTML = generateUUID2();