保留两位小数

toDecimal2: function (x) {
            var f = parseFloat(x);
            if (isNaN(f)) {
                return false;
            }
            var f = Math.round(x * 100) / 100;
            var s = f.toString();
            var rs = s.indexOf('.');
            if (rs < 0) {
                rs = s.length;
                s += '.';
            }
            while (s.length <= rs + 2) {
                s += '0';
            }
            return s;
        }
    }