年月日

   this.years = [];
    for (let i = 1970; i <= 2100; ++i) {
      this.years.push(i);
    }
    this.months = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12];
    this.daysCount = [
      [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],
      [31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31],
    ];



  isLeapYear(year) {
    return year % 4 === 0 && (year % 100 !== 0 || year % 400 === 0);
  }



    let daysCount = this.daysCount[this.isLeapYear(year) ? 1 : 0][month];
    if (day > daysCount) {
      day = daysCount;
      date.setDate(day);
      date.setMonth(month);
    } else {
      date.setMonth(month);
      date.setDate(day);
    }