ES6 三点运算符

<script type="text/javascript">
   let fun=(...param)=>{
       console.log(param);
       //遍历参数
       param.forEach((item,value)=>{
           console.log(item,value);
       })
   }
   fun(1,2,3,4)//打印一个数组
</script>

<script type="text/javascript">
   //拼接数组
   let arr1=[];
   let arr2 = [7,8,9];
   arr1=[0,...arr2];
   console.log(arr1);//[0,7,8,9]
   console.log(...arr2);//7 8 9
</script>