JS 保留2位小数 四舍五入（小数点后面不足2位，自动用0补齐）

function changeTwoDecimal_f(x) {
 ???var f_x = parseFloat(x);
 ???if (isNaN(f_x)) {
 ???????alert(‘function:changeTwoDecimal->parameter error‘);
 ???????return false;
 ???}
 ???var f_x = Math.round(x * 100) / 100;
 ???var s_x = f_x.toString();
 ???var pos_decimal = s_x.indexOf(‘.‘);
 ???if (pos_decimal < 0) {
 ???????pos_decimal = s_x.length;
 ???????s_x += ‘.‘;
 ???}
 ???while (s_x.length <= pos_decimal + 2) {
 ???????s_x += ‘0‘;
 ???}
 ???return s_x;
}

参考链接：http://www.jb51.net/article/45884.htm