uuid.js

// On creation of a UUID object, set it's initial value
function UUID(){
    this.id = this.createUUID();
}

// When asked what this Object is, lie and return it's value
UUID.prototype.valueOf = function(){ return this.id; };
UUID.prototype.toString = function(){ return this.id; };

//
// INSTANCE SPECIFIC METHODS
//
UUID.prototype.createUUID = function(){
    //
    // Loose interpretation of the specification DCE 1.1: Remote Procedure Call
    // since JavaScript doesn't allow access to internal systems, the last 48 bits
    // of the node section is made up using a series of random numbers (6 octets long).
    //  
    var dg = new Date(1582, 10, 15, 0, 0, 0, 0);
    var dc = new Date();
    var t = dc.getTime() - dg.getTime();
    var tl = UUID.getIntegerBits(t,0,31);
    var tm = UUID.getIntegerBits(t,32,47);
    var thv = UUID.getIntegerBits(t,48,59) + '1'; // version 1, security version is 2
    var csar = UUID.getIntegerBits(UUID.rand(4095),0,7);
    var csl = UUID.getIntegerBits(UUID.rand(4095),0,7);

// since detection of anything about the machine/browser is far to buggy,
    // include some more random numbers here
    // if NIC or an IP can be obtained reliably, that should be put in
    // here instead.
    var n = UUID.getIntegerBits(UUID.rand(8191),0,7) +
            UUID.getIntegerBits(UUID.rand(8191),8,15) +
            UUID.getIntegerBits(UUID.rand(8191),0,7) +
            UUID.getIntegerBits(UUID.rand(8191),8,15) +
            UUID.getIntegerBits(UUID.rand(8191),0,15); // this last number is two octets long
    return tl + tm  + thv  + csar + csl + n;
};

//Pull out only certain bits from a very large integer, used to get the time
//code information for the first part of a UUID. Will return zero's if there
//aren't enough bits to shift where it needs to.
UUID.getIntegerBits = function(val,start,end){
 var base16 = UUID.returnBase(val,16);
 var quadArray = new Array();
 var quadString = '';
 var i = 0;
 for(i=0;i<base16.length;i++){
     quadArray.push(base16.substring(i,i+1));    
 }
 for(i=Math.floor(start/4);i<=Math.floor(end/4);i++){
     if(!quadArray[i] || quadArray[i] == '') quadString += '0';
     else quadString += quadArray[i];
 }
 return quadString;
};

//Replaced from the original function to leverage the built in methods in
//JavaScript. Thanks to Robert Kieffer for pointing this one out
UUID.returnBase = function(number, base){
 return (number).toString(base).toUpperCase();
};

//pick a random number within a range of numbers
//int b rand(int a); where 0 <= b <= a
UUID.rand = function(max){
 return Math.floor(Math.random() * (max + 1));
};