楼层号按顺序进行筛选，且不重复的方法（优化版）

上次的方法不适合大量添加，且不适合一次性添加多个在选择，这次通过使用优化的方法进行判断，功能强大了。

 <div id="app">
      <div>
        <ul>
          <li v-for="(item,index) in floorlist" :key="index">
            <span>{{item.floor}}</span>
            <select
              v-model="item.floor"
              :disabled="index === 0 || index === floorlist.length - 1"
            >
              <option
                v-for="items in vilidarFloor(floorlist, index, floors)"
                :key="items.label"
                :label="items.label"
                :value="items.value"
              ></option>
            </select>
            <button @click="del(index)">删除一行</button>
            <button @click="add(index)">添加一行</button>
          </li>
        </ul>
      </div>
    </div>
    <script src="vue.js"></script>
    <script>
      const vm = new Vue({
        el: '#app',
        data: {
          floors: [1, 2, 3, 4, 5, 6, 7, 8, 9, 12, 34],
          floorlist: []
        },
        created() {
          this.floorlist = [
            { id: 1, floor: this.floors[this.floors.length - 1] },
            { id: 2, floor: this.floors[0] }
          ];
        },
        methods: {
          add(index) {
            this.floorlist.splice(index + 1, 0, {
              id: Math.random(),
              floor: ''
            });
            console.log(this.floorlist);
          },
          del(index) {
            this.floorlist.splice(index, 1);
          },
          vilidarFloor(floorlist, index, floors) {
            floors = floors.map(item => {
              return { value: item, label: item };
            });
            const floorlimit = {};
            //遍历上层区
            for (let i = index - 1; i >= 0; i--) {
              const floorNo = floorlist[i].floor;
              if (floorNo) {
                floorlimit.higher = floorNo;
                break;
              }
            }
            //遍历下层区
            for (let i = index + 1; i <= floorlist.length - 1; i++) {
              const floorNo = floorlist[i].floor;
              if (floorNo) {
                floorlimit.lower = floorNo;
                break;
              }
            }
            // console.log('lim', floorlimit);
            let result = {};
            if (index === 0 || index === floorlist.length - 1) {
              result = floors;
            } else {
              result = floors.filter(
                item =>
                  item.value > floorlimit.lower &&
                  item.value < floorlimit.higher
              );
            }
            return result.reverse();
          }
        }
      });
    </script>

之间cv大法进行看效果：