JS 四舍五入自定义小数位数，空缺补0

<mce:script type="text/javascript"><!-- //JS 四舍五入自定义小数位数，空缺补0 function formatnumber(value, num) { var a, b, c, i; a = value.toString(); b = a.indexOf("."); c = a.length; if (num == 0) { if (b != -1) { a = a.substring(0, b); } } else { if (b == -1) { a = a + "."; for (i = 1; i <= num; i++) { a = a + "0"; } } else { a = a.substring(0, b + num + 1); for (i = c; i <= b + num; i++) { a = a + "0"; } } } return a; } //public cyj //对数字进行四舍五入计算 function round(num,n){ var dd=1; var tempnum; for(i=0;i<n;i++){ dd*=10; } tempnum=num*dd; tempnum=Math.round(tempnum); return formatnumber(tempnum/dd,n); } // --></mce:script> <mce:script type="text/javascript"><!-- alert(round(3.2436,2)); // --></mce:script>