js 计算年龄

function calculateAge(birthDate) {
  var birthDate = new Date(birthDate);
  var differenceInMS = Date.now() - birthDate.getTime();
  var ageDate = new Date(differenceInMS); // 毫秒转换为日期
  return Math.abs(ageDate.getUTCFullYear() - 1970);
}

// 使用示例
var birthYear = '1990-01-01';
console.log("年龄是: " + calculateAge(birthYear) + " 岁");

function calculateAge(birthDate) {
  var birthDate = new Date(birthDate);
  var today = new Date();
  var age = today.getFullYear() - birthDate.getFullYear();
  var monthDifference = today.getMonth() - birthDate.getMonth();
  
  // 如果当前月份小于出生月份，或者月份相同但当前日期小于出生日期，则年龄减一
  if (monthDifference < 0 || (monthDifference === 0 && today.getDate() < birthDate.getDate())) {
    age--;
  }
  
  return age;
}

// 使用示例
var birthYear = '1990-01-01';
console.log("年龄是: " + calculateAge(birthYear) + " 岁");