js 正则表达式 验证小数点后几位

function IsFloatByBit (value, state, bit) {

            if (state == false) {

                var reg = new RegExp("^\\d+(\\.\\d{" + bit + "})*$", "ig");

                return reg.test(value);

            } else {

                var reg = new RegExp("^[-]?\\d+(\\.\\d{" + bit + "})*$", "ig");

                return reg.test(value);

            }

        }