Javascript 如何取小数点后面N位

1.最基本的方法

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

2. 正则表达式效果不错

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

3.推荐选择

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

4.需要 IE5.5+才支持。
<scrīpt>
var num=22.127456;
alert( num.toFixed(2));
</scrīpt>