<script type="text/javascript">
var num=0;
function numCount(){
document.getElementById('txt').value=num;
num=num+1;
setTimeout("numCount()",1000);
}
</script>

函數(shù)運行思路，1.第二個setTimeout調(diào)用numCount函數(shù)? 2.numCount函數(shù)中的setTimeout又調(diào)用numCount，周而復始反復調(diào)用下去！

用一個函數(shù)來封裝一下：

function example(){
//其他語句;
 ? ? ? ?setTimeout("example()",1000);
}
setTimeout("example()",1000);