a fast clock times a slow clock and uses a factor of the difference to build a un-predictable 36 alphabet string

nonce maker.js

function nonce(chars){
    var b="", round, last;
    while(true){
        var round= (Date.now() / (performance.now()*1000)).toString(36).split(".").pop().slice(2, -2);
        if(round!=last) b+= round;
        if(b.length > chars) break;
        last=round;
    }
   return b.slice(-chars);
}