weak guid example
JavaScript
var x = 1000;
while(x-- > 0){
var a = '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);
}).length;
document.writeln(a + "<br/>");
}