https://blog.csdn.net/weixin_41941325/article/details/80936603 (opens new window)

 <van-button   
    v-for="(item,index) in  showYearList"
    :key="index"
    >{{item}}
 </van-button>

 <van-button @click="changeFold('year')"  size="small">{{yearFold?'更多':'收起'}}</van-button>

computed:{
  showYearList: {
      get() {
        if (this.yearFold) {
          if (this.yearList.length < 4) {
            return this.yearList;
          }
          const newArr = [];
          for (let i = 0; i < 4; i++) {
            const item = this.yearList[i];
            newArr.push(item);
          }
          return newArr;
        }
        return this.yearList;
      },
      set(val) {
        this.showYearList = val;
      },
  }
}
   changeFold(){
      this.yearFold = !this.yearFold;
   }