要求：点击el-date-picker选择时间范围时，默认展开当月和上个月。

但是Element UI的组件默认展开的是本月和下一个月，如下图所示：

改为

<span @click="changeInitCalendarRange">
    <el-date-picker v-model="ruleForm.time" type="datetimerange" value-format="yyyy-MM-dd HH:mm:ss"
                range-separator="至" start-placeholder="开始日期" end-placeholder="结束日期" :picker-options="pickerOptions" @change="onsetmonitor" @blur="blur"
                class="form-width">
    </el-date-picker>
</span>

<script>
export default {
    data() {
        return {
            pickerOptions: {
                disabledDate(time) {
                    return time.getTime() > Date.now() - 8.64e7 || time.getTime() < Date.now() - 8.64e7 * 90;
            },
            shortcuts: [
              {
                text: '最近一周',
                onClick(picker) {
                  const end = new Date();
                  const start = new Date();
                  start.setTime(start.getTime() - 3600 * 1000 * 24 * 7);
                  picker.$emit('pick', [start, end]);
                },
              },
              {
                text: '最近一个月',
                onClick(picker) {
                  const end = new Date();
                  const start = new Date();
                  start.setTime(start.getTime() - 3600 * 1000 * 24 * 30);
                  picker.$emit('pick', [start, end]);
                },
              },
              {
                text: '最近三个月',
                onClick(picker) {
                  const end = new Date();
                  const start = new Date();
                  start.setTime(start.getTime() - 3600 * 1000 * 24 * 90);
                  picker.$emit('pick', [start, end]);
                },
              },
            ],
          },
        };
    },
    methods: {
        /**时间范围选择器，组件默认展示上月和本月  点击判断**/
        changeInitCalendarRange() {
          if(this.countss > 0){
            return
          }else{
              this.countss++
              let element = document.querySelector("button.el-picker-panel__icon-btn.el-icon-arrow-left");
              if (element){
                element.click()
              };
          };
        },
        //多次点击清空按钮
        blur(){
          if(this.ruleForm.time == null){
              this.countss = 0;
            }
        },
        //如果选定值，重置countss
        onsetmonitor(){
          if(this.ruleForm.time){
            return
          };
          this.countss = 0
        },
    }
}