• 1.concat() 方法用于连接两个或多个数组。

该方法不会改变现有的数组，而仅仅会返回被连接数组的一个副本

arrayObject.concat(arrayX,arrayX,......,arrayX)

• 2.在数组中添加数字

  <script type="text/javascript">
  
      var a = [1,2,3];
      console.log(a.concat(4,5)); // a = [1,2,3,4,5]
  
    </script>
  

• 3.连接两个数组

  <script type="text/javascript">
  
    var arr = new Array(3)
    arr[0] = "1"
    arr[1] = "2"
     arr[2] = "3"
  
     var arr2 = new Array(3)
     arr2[0] = "4"
     arr2[1] = "5"
     arr2[2] = "6"
  
     console.log(arr.concat(arr2))； //  [1,2,3,4,5,6]
  
      var arr3 = [1,2,3];
      var arr4 = [7,8,9];
      var arr5 = arr3.concat(arr4)
      console.log(arr5)； // arr5 = [1, 2, 3, 7, 8, 9]
   </script>