方法有两个参数，第一个形参传身份证号，第二个形参传num。
num=1代表返回出生日期。num=2代表返回性别。num=3代表返回年龄。
//通过身份证号计算年龄、性别、出生日期function idCard(userCard, num) {//获取出生日期if (num == 1) {birth = userCard.substring(6, 10) + "-" + userCard.substring(10, 12) + "-" + userCard.substring(12, 14);return birth;}//获取性别if (num == 2) {if (parseInt(userCard.substr(16, 1)) % 2 == 1) {return "男";} else {return "女";}}//获取年龄if (num == 3) {var myDate = new Date();var month = myDate.getMonth() + 1;var day = myDate.getDate();var age = myDate.getFullYear() - UUserCard.substring(6, 10) - 1;if (userCard.substring(10, 12) < month || userCard.substring(10, 12) == month && userCard.substring(12, 14) <= day) {age++;}return age;}}
