[JavaScript知识库]JS获取去年日期（包含闰年逻辑）

// 获取日期
function getDay(d, num) {
  const date = new Date(new Date(d).setDate(new Date(d).getDate() + num))
  const year = date.getFullYear()
  const month = (date.getMonth() + 1 + "").padStart(2, "0")
  const day = (date.getDate() + "").padStart(2, "0")
  return `${year}-${month}-${day}`
}

// 返回去年日期，根据去年是否是闰年会有所区别
function lastYearDate(d) {
  const lastYear = new Date(d).getFullYear() - 1
  // 去年是否是闰年
  const lastYearIsLeap = (lastYear % 4 == 0 && lastYear % 100 != 0) || lastYear % 400 == 0
  if (lastYearIsLeap) return getDay(d, -366)
  return getDay(d, -365)
}

// 测试
const date = "2021-2-10"
console.log(lastYearDate(date)) // 2020-02-10
const date1 = "2021-3-1"
console.log(lastYearDate(date1)) // 2020-02-29
const date2 = "2021-3-10"
console.log(lastYearDate(date2)) // 2020-03-09

const date3 = "2020-2-10"
console.log(lastYearDate(date3)) // 2019-02-10
const date4 = "2020-2-29"
console.log(lastYearDate(date4)) // 2019-03-01
const date5 = "2020-3-10"
console.log(lastYearDate(date5)) // 2019-03-11

const date6 = "2023-3-1"
console.log(lastYearDate(date6)) // 2022-03-01

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