js读取小数点后几位方法

1.

function get()
{
    var s = 22.127456 + "";
    var str = s.substring(0,s.indexOf(".") + 3);
    alert(str);
}

2. 

<script type="text/javascript">
onload = function(){
    var a = "23.456322";
    var aNew;
    var re = /([0-9]+\.[0-9]{2})[0-9]*/;
    aNew = a.replace(re,"$1");
    alert(aNew);
}
</script>

3. 推荐

<script>
var num=22.127456;
alert( Math.round(num*100)/100);
</script>

4.需要 IE5.5+才支持。

 <script>
var num=22.127456;
alert( num.toFixed(2));
</script>