javascript小數四舍五入 
用Javascript取float型小數點后兩位，例22.127456取成22.13,如何做？ 

1. 最笨的辦法....... [我就怎么干的.........] 

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

2. 正則表達式效果不錯 

<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. 他就比較聰明了..... 

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

4.會用新鮮東西的朋友....... 但是需要 IE5.5+才支持。 

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