arr-map的练习

  <script>
          var arr = [
            "添加",
            "时候收到的哈哈哈",
            "啥开始看阿萨斯",
            "是好还是坏"
        ]
       var res= arr.map(item=>{
           if(item.length>3){
               item = item.substr(0,3)+"..."
           }
            return  item
        });
        console.log(res)
    </script>