<script language="javascript">
document.write("<h1>JS保留兩位小數例子</h1><br>"); 
var a=2.1512131231231321;   
document.write("原來的值："+a+"<br>");   
document.write("兩位小數點:"+a.toFixed(2)+"<br>四位小數點"+a.toFixed(4));
</script>