javascript 年月日级联菜单

Posted 2021-05-04

现在世界通用的公历（阳历）也经过一个长期演变的过程。我们先看，公历每个月的日数是固定的：
"七前单大，八后双大"。也就是说，一、三、五、七、八、十、腊月（十二月）是31天，
四、六、九、十一月是30天，只有二月，平年28天，闰年29天。
let cascader={     
      creatYear () {
        let years = []
        let year = new Date().getFullYear()
        let minYear = year - 100
        for (let i = year; i >= minYear; i--) {
          years.push(i)
        }
        this.years = years
      },
      creatMonth () {
        let months = []
        for (let i = 0; i < 12; i++) {
          months.push(i + 1)
        }
        this.months = months
      },
      creatDay (year, month) {
        let days = []
        let day
        switch (month) {
          case 1:
          case 3:
          case 7:
          case 8:
          case 10:
          case 12:
            day = 31
            break
          case 4:
          case 6:
          case 9:
          case 11:
            day = 30
            break
          case 2:
            day = IsRunYear(year) ? 29 : 28
            break
          default:
            day = 31
        }
        function IsRunYear (year) {
          return (year % 4 === 0 && year % 100 !== 0) || year % 400 === 0
        }
        for (let i = 0; i < day; i++) {
          days.push(i + 1)
        }
        return days
      }
      
}