Question

<script>
    window.onload= function(){
        var a = document.getElementById('a');
        var b = document.getElementById('ct');
        setInterval('b.innerHTML = a.duration',1000);
   };
</script>
//Second  script
<script>
    var a = document.getElementById('a');
    var b = document.getElementById('ct');
    window.onload= function(){
        setInterval('b.innerHTML = a.duration',1000);
    };
</script>

Why the first script is not working?.

Chrome:

Uncaught ReferenceError: b is not defined

Answer 1

My guess would be: because you use var on a and b in the first script. This makes the variables local ones in window.onload (instead of global), and the code in setInterval cannot access them.

Remove the var and it should work.