js取小数点后两位四种方法

function getnum(){var num = 22.123456;var result = num.substring(0,s.indexOf(".")+3);alert(result);}

function getnum(){var num = 22.123456;var aNew;var re = /([0-9]+/.[0-9]{2})[0-9]*/;aNew = num.replace(re,"$1");alert(aNew);}

function getnum(){var num=22.123456;alert( Math.round(num*100)/100);}

alert(num.toFixed(2));