18位身份证需要验证最后一位校验位

//18位身份证需要验证最后一位校验位

            value = value.split('');
            //∑(ai×Wi)(mod 11)
            //加权因子
            var factor = [7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2];
            //校验位
            var parity = [1, 0, 'X', 9, 8, 7, 6, 5, 4, 3, 2];
            var sum = 0;
            var ai = 0;
            var wi = 0;
            for (var i = 0; i < 17; i++) {
                ai = value[i];
                wi = factor[i];
                sum += ai * wi;
            }
            var last = parity[sum % 11];
            if (parity[sum % 11] != value[17]) {
                this.showErrMsg(sender, "无效的身份证号，请重新输入！");
                return false;
            }