日期判断只能选择本月之前的日期

 <DatePicker type="date" :options="options3" format="yyyy-MM-dd"
                                  placeholder="请选择时间"
                                  style="width: 200px"></DatePicker>

js

 options3: {
          disabledDate (date) {
            function myMonth(year, month){
              let d = new Date(year, month, 0);
              return d.getDate();
            };
　　　　　　//a 是举例的，大家可以尝试一下
            let time,a='2020-01-01';
            let dateNow = new Date(a);
            if (dateNow.getMonth() != 0) {
              time = dateNow.getFullYear() + '-' + dateNow.getMonth() + '-' + myMonth(dateNow.getFullYear(), dateNow.getMonth());
            } else {
              time = dateNow.getFullYear()-1 + '-' + 12 + '-' + myMonth(dateNow.getFullYear(), 12);
            }
            let newDate = new Date(time).getTime();
            return date && date.valueOf() > newDate;
          }
        },