var a = new array();

var b = new array(8);

var c = new array("first", "second","third");

或者數組直接量：

var d = ["first", "second","third"];

下面看一下，在數組后面增加一個元素

var myarray = [];

myarray[myarray.length] = 'new element';

數組的長度

array只有一個屬性，就是length，length表示的是數組所占內存空間的數目，而不僅僅是數組中元素的個數，在剛才定義的數組中，b.length的值為8

<script>

var a = new array("first", "second","third")

a[48] = "12"

document.write(a.length)

//顯示的結果是49

</script>

下面來看看修改數組長度實例

var myarray = [1,2,3];

myarray.length // 3

myarray.length = 2; //delete the last element

myarray.length = 20 // add 18 elements to the array; theelements have the undefined value.