Js 扩展

计算字符串的字节长度
String.prototype.len = function () {
    return this.replace(/[^\x00-\xff]/g, 'xx').length;
};
alert(t.Calendar.len());

//保留两位小数
        //功能：将浮点数四舍五入，取小数点后2位
        function toDecimal(x) {
            var f = parseFloat(x);
            if (isNaN(f)) {
                return;
            }
            f = Math.round(x*100)/100;
            return f;
        }

4.00

function toDecimal2(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;
        }