【工具方法】getAge

williamzhou 4/2/2021 面试编程能力

# 参考资料

MDN定义 - Date (opens new window)

# 问题

根据出生年月计算年龄

约定：过了 x 岁生日后一天才算 x 岁

注意事项：

参数合法性校验
边界条件
UTC时间

# 代码实现

/**
 * @param {String} birthday 出生年月日
 * @returns {Number} 年龄
 */
function getAge(birthday) {
  const validator = new RegExp(/^\d{4}-\d{2}-\d{2}$/)
  if (!validator.test(birthday)) {
    throw new Error(`invalid argument ${birthday}`)
  }

  const [birthYear, birthMonth, birthDay] = birthday.split('-').map(str => Number(str))
  const now = new Date()
  const nowYear = now.getFullYear()
  const nowMonth = now.getMonth() + 1
  const nowDay = now.getDate()

  const age = nowYear - birthYear - 1
  if (nowMonth > birthMonth || (nowMonth === birthMonth && nowDay > birthDay)) {
    return age + 1
  } else {
    return age
  }
}

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# 测试一下

var log = console.log
log(getAge('1995-09-12'))
log(getAge('1995-03-26'))
log(getAge('1995-03-27'))
log(getAge('1995-03-28'))

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