<el-input
  type="textarea"
  :autosize="autosize"
  placeholder="请输入内容"
  v-model="value">
</el-input>

<script>
data(){
          return {
            value : '',
            screenWidth: document.body.clientWidth,
            timer:false,
            autosize:{ minRows: 2 }
          }
      },
       mounted () {
    
        window.onresize = () => {
          return (() => {
            window.screenWidth = document.body.clientWidth
            this.screenWidth = window.screenWidth
          })()
        }
      },
         watch:{
        screenWidth(val){
          // 为了避免频繁触发resize函数导致页面卡顿，使用定时器
          if(!this.timer){
            // 一旦监听到的screenWidth值改变，就将其重新赋给data里的screenWidth
            this.screenWidth = val
            this.timer = true
            let that = this
            setTimeout(function(){
              // 打印screenWidth变化的值
              console.log(that.screenWidth)
              if(that.screenWidth <= 1536){
                that.$set(that.autosize , 'minRows' , 2);
              }else {
                that.$set(that.autosize , 'minRows' , 3);
              }
              that.timer = false
            },400)
          }
        }
      },
</script>