Trying to make a random string generator with animation
<p>I'm trying to create a string randomiser with animation but its not working.</p>

<p>I use this function to call the function following a Frame rate that the browser picks:</p>

<pre><code>window.requestAnimFrame = (function(){
  return  window.requestAnimationFrame       || 
          window.webkitRequestAnimationFrame || 
          window.mozRequestAnimationFrame    || 
          window.oRequestAnimationFrame      || 
          window.msRequestAnimationFrame     || 
          function( callback,  element){
            window.setTimeout(callback, 1000 / 60);
          };
})();
</code></pre>

<p>Followed by this as my method to generate and display the string:</p>

<pre><code>function create(chars,string_length){
output = [];
var randomstring = '';
    for (var i=0; i&lt;string_length; i++) {
        var rnum = Math.floor(Math.random() * chars.length);
        randomstring += chars.substring(rnum,rnum+1);
    }


    output.push(randomstring);

    document.getElementById('cb').innerHTML = (output.join(''));
}


var chars =  "ABCDEFGHIJKLMNOPQRSTUVWXTZabcdefghiklmnopqrstuvwxyz";
var length = 20;

requestAnimFrame( create(chars,length) );
</code></pre>

<p>It generates a string to my div 'id' but only once - so the function working but it is not being called all the time =/</p>

<p>Why would this be ?</p>
