javascript - 为什么它在 document.onload 中不起作用？

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>

为什么第一个脚本不起作用？

Chrome :

Uncaught ReferenceError: b is not defined

Answer 1

您需要指定一个函数作为 setInterval 的参数，这里有问题:

setInterval('b.innerHTML = a.duration',1000);

应该是:

setInterval(function foo(){b.innerHTML = a.duration},1000);