js concat什么时候用

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

<script type="text/javascript">

var a = [1,2,3];

document.write(a.concat(4,5));

</script>

1,2,3,4,5

<script type="text/javascript">

var arr = new Array(3)

arr[0] = "George"

arr[1] = "John"

arr[2] = "Thomas"

var arr2 = new Array(3)

arr2[0] = "James"

arr2[1] = "Adrew"

arr2[2] = "Martin"

document.write(arr.concat(arr2))

</script>

George,John,Thomas,James,Adrew,Martin