Cryptography

Javascript: Generate a GUID

AlexBLeave a comment

How to create a GUID in Javascript

Two years ago, I needed to generate GUID for an ExtJS project (purpose was to create on-the-fly a unique id for tchat messages user was sending). Hereafter the function I used (source should by StackOverFlow and other forums, I dont’ remember exactly), still working.

generateGUID : function() {
  return ((typeof(window.crypto) != 'undefined' 
      && typeof(window.crypto.getRandomValues) != 'undefined') 
    ? function() { // If we have a cryptographically secure PRNG
        var buf = new Uint16Array(8);
        window.crypto.getRandomValues(buf);
        var S4 = function(num) {
          var ret = num.toString(16);
          while(ret.length < 4){ ret = "0"+ret; }
          return ret;
        };
        return (S4(buf[0])+S4(buf[1])+"-"
            +S4(buf[2])+"-"+S4(buf[3])+"-"
            +S4(buf[4])+"-"+S4(buf[5])+S4(buf[6])+S4(buf[7]));
      }
    : function() { // Otherwise, just use Math.random
        return 'xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx'
                .replace(
                        /[xy]/g, 
                        function(c) {
                          var r = Math.random()*16|0,
                              v = c == 'x' ? r : (r&0x3|0x8);
                          return v.toString(16);
                        }
                ); // replace
      }
   )(); 
}// generateGUID

Couple of references: