1.length;获取数组的长度；

<script type="text/javascript">

var txt="Hello World!"
document.write(txt.length)

</script>

输出：

12

2.push();将值添加到数组的尾部；

<script type="text/javascript">

var arr = new Array(3)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"

document.write(arr + "<br />")
document.write(arr.push("James") + "<br />")
document.write(arr)

</script>

输出：

George,John,Thomas
4
George,John,Thomas,James

3.unshift();将值添加数组的头部;

<script type="text/javascript">

var arr = new Array()
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"

document.write(arr + "<br />")
document.write(arr.unshift("William") + "<br />")
document.write(arr)

</script>

输出：

George,John,Thomas
4
William,George,John,Thomas

4.pop()；删除数组的最后一个元素，并且返回删除元素;

 var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.pop();

fruits 结果输出：
Banana,Orange,Apple

5.splice();从一个数组当中删除一个或多个元素，返回所移除的元素；

<script type="text/javascript">

var arr = new Array(6)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"
arr[3] = "James"
arr[4] = "Adrew"
arr[5] = "Martin"

document.write(arr + "<br />")
arr.splice(2,0,"William")
document.write(arr + "<br />")

</script>

输出：

George,John,Thomas,James,Adrew,Martin
George,John,William,Thomas,James,Adrew,Martin

6.slice(): 方法可从已有的数组中返回选定的元素.

<script type="text/javascript">

var arr = new Array(3)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"

document.write(arr + "<br />")
document.write(arr.slice(1) + "<br />")
document.write(arr)

</script>

输出：

George,John,Thomas
John,Thomas
George,John,Thomas

7.concat(arr1,arr2);将多个数组合并为一个数组，并且返回合并数组；

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"
 
var arr3 = new Array(2)
arr3[0] = "William"
arr3[1] = "Franklin"
 
document.write(arr.concat(arr2,arr3))//返回结果George,John,Thomas,James,Adrew,Martin,William,Franklin

8.join(“分隔符”);将数组转换为字符串，字符串按照分隔符分割，返回分割好的字符串

<script type="text/javascript">

var arr = new Array(3)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"

document.write(arr.join())

</script>

输出：

George,John,Thomas

9.reverse();反转数组，返回翻转后的数组；

<script type="text/javascript">

var arr = new Array(3)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"

document.write(arr + "<br />")
document.write(arr.reverse())

</script>

输出：

George,John,Thomas
Thomas,John,George

10.concat():基于当前数组，创建一个新的数组，并返回这个新数组，不会改变原数组；

var color = ["red","green","blue"];
var colors2 = color.concat("yellow",["black","brown"]);

11.shift():方法用于把数组的第一个元素从其中删除，并返回第一个元素的值。

<script type="text/javascript">

var arr = new Array(3)
arr[0] = "George"
arr[1] = "John"
arr[2] = "Thomas"

document.write(arr + "<br />")
document.write(arr.shift() + "<br />")
document.write(arr)

</script>

输出：

George,John,Thomas
George
John,Thomas

12.String() :对象用于处理文本（字符串）。

new String(s);
String(s);