基于Vue3实现一个日期计算器的操作方案

const dateDiff = computed(() => {
  if (!startDate.value || !endDate.value) {
    return { days: 0, weeks: 0, months: 0, years: 0 }
  }

  const start = new Date(startDate.value)
  const end = new Date(endDate.value)

  // 确保开始日期小于结束日期(自动排序)
  const [earlierDate, laterDate] = start <= end ? [start, end] : [end, start]

  let diffTime = laterDate.getTime() - earlierDate.getTime()

  // 如果包含结束日期,增加一天
  if (includeEndDate.value) {
    diffTime += 24 * 60 * 60 * 1000
  }

  const diffDays = Math.floor(diffTime / (1000 * 60 * 60 * 24))

  // 计算精确的月数差异
  let months = (laterDate.getFullYear() - earlierDate.getFullYear()) * 12
  months += laterDate.getMonth() - earlierDate.getMonth()

  // 如果日期不足一个月,减去一个月
  if (laterDate.getDate() < earlierDate.getDate()) {
    months--
  }

  // 计算年数
  const years = Math.floor(months / 12)

  return {
    days: diffDays,
    weeks: Math.floor(diffDays / 7),
    months: Math.max(0, months),
    years: Math.max(0, years)
  }
})

// 交换开始和结束日期
const swapDates = () => {
  const temp = startDate.value
  startDate.value = endDate.value
  endDate.value = temp
}

// 设置结束日期为今天
const setToday = (type) => {
  if (!process.client) return
  const today = new Date().toISOString().split('T')[0]
  if (type === 'diff') {
    endDate.value = today
  }
}

const calculatedDate = computed(() => {
  if (!baseDate.value) {
    return ''
  }

  if (!amount.value || amount.value === 0) {
    return baseDate.value
  }

  const base = new Date(baseDate.value)
  // 根据操作类型确定正负
  const value = operation.value === 'add' ? parseInt(amount.value) : -parseInt(amount.value)

  switch (unit.value) {
    case 'days':
      base.setDate(base.getDate() + value)
      break
    case 'weeks':
      base.setDate(base.getDate() + (value * 7))
      break
    case 'months':
      base.setMonth(base.getMonth() + value)
      break
    case 'years':
      base.setFullYear(base.getFullYear() + value)
      break
  }

  return base.toISOString().split('T')[0]
})

const getWeekday = (dateStr) => {
  if (!dateStr) return ''
  const weekdays = tm('dateCalculator.weekdays')
  if (!weekdays || !Array.isArray(weekdays)) return ''
  const date = new Date(dateStr)
  return weekdays[date.getDay()] || ''
}

const age = computed(() => {
  if (!birthDate.value || !ageCalculateDate.value) {
    return { years: 0, months: 0, days: 0, totalDays: 0 }
  }

  const birth = new Date(birthDate.value)
  const calculate = new Date(ageCalculateDate.value)

  // 如果出生日期晚于计算日期,返回0
  if (birth > calculate) {
    return { years: 0, months: 0, days: 0, totalDays: 0 }
  }

  // 计算精确年龄
  let years = calculate.getFullYear() - birth.getFullYear()
  let months = calculate.getMonth() - birth.getMonth()
  let days = calculate.getDate() - birth.getDate()

  // 调整天数
  if (days < 0) {
    months--
    // 获取上个月的天数
    const lastMonth = new Date(calculate.getFullYear(), calculate.getMonth(), 0)
    days += lastMonth.getDate()
  }

  // 调整月数
  if (months < 0) {
    years--
    months += 12
  }

  // 计算总天数
  const totalDays = Math.floor((calculate.getTime() - birth.getTime()) / (1000 * 60 * 60 * 24))

  return {
    years: Math.max(0, years),
    months: Math.max(0, months),
    days: Math.max(0, days),
    totalDays: Math.max(0, totalDays)
  }
})

// 模板中使用
Math.floor(age.totalDays / 30.44)  // 总月数(平均每月30.44天)
Math.floor(age.totalDays / 7)      // 总周数
age.totalDays                      // 总天数

const workDays = computed(() => {
  if (!workStartDate.value || !workEndDate.value) {
    return { total: 0, weekdays: 0, weekends: 0 }
  }

  const start = new Date(workStartDate.value)
  const end = new Date(workEndDate.value)

  // 确保开始日期不大于结束日期
  if (start > end) {
    return { total: 0, weekdays: 0, weekends: 0 }
  }

  let weekdays = 0
  let weekends = 0
  const current = new Date(start)

  // 包含开始和结束日期
  while (current <= end) {
    const dayOfWeek = current.getDay()
    if (dayOfWeek === 0 || dayOfWeek === 6) { // 周日=0, 周六=6
      weekends++
    } else {
      weekdays++
    }
    current.setDate(current.getDate() + 1)
  }

  return {
    total: weekdays + weekends,
    weekdays: excludeWeekends.value ? weekdays : weekdays + weekends,
    weekends
  }
})

// Tab 切换
const activeTab = ref('difference')

// 日期间隔计算
const startDate = ref('')
const endDate = ref('')
const includeEndDate = ref(false)

// 日期加减计算
const baseDate = ref('')
const operation = ref('add')      // 'add' | 'subtract'
const amount = ref(0)
const unit = ref('days')          // 'days' | 'weeks' | 'months' | 'years'

// 工作日计算
const workStartDate = ref('')
const workEndDate = ref('')
const excludeWeekends = ref(true)

// 年龄计算
const birthDate = ref('')
const ageCalculateDate = ref('')

onMounted(() => {
  if (!process.client) return
  const today = new Date().toISOString().split('T')[0]
  startDate.value = today
  endDate.value = today
  baseDate.value = today
  workStartDate.value = today
  workEndDate.value = today
  birthDate.value = ''  // 不设置默认出生日期
  ageCalculateDate.value = today
})

// JavaScript 的 Date 会自动处理溢出
const date = new Date('2024-01-31')
date.setMonth(date.getMonth() + 1)  // 自动变为 2024-03-02(2月没有31日)

// 将日期设为0,会自动回退到上月最后一天
const lastDayOfLastMonth = new Date(year, month, 0)

// ISO 格式转 YYYY-MM-DD
const dateStr = new Date().toISOString().split('T')[0]

日期间隔计算:
  时间戳相减 → 转换为天数
  年月日逐级计算 → 处理借位

日期加减计算:
  原生 Date API → 自动处理溢出

年龄计算:
  年月日分别相减 → 逐级调整借位

工作日计算:
  逐日遍历 → 判断星期几 → 统计分类