<script language="javascript">
document.write("<h1>JS保留两位小数例子</h1><br>"); 
var a=2.1512131231231321;   
document.write("原来的值："+a+"<br>");   
document.write("两位小数点:"+a.toFixed(2)+"<br>四位小数点"+a.toFixed(4));
</script>