JavaScript基础学习（三）----Array数组对象

1、创建数组

<script>

var i;
var mycars = new Array();
mycars[0] = "Saab";
mycars[1] = "Volvo";

mycars[2] = "BMW";

for (i=0;i<mycars.length;i++)
{
document.write(mycars[i] + "<br>");
}

</script>

2.合并两个数组--concat()

function myFunction()
{
var hege = ["Cecilie", "Lone"];
var stale = ["Emil", "Tobias", "Linus"];
var children = hege.concat(stale);
var x=document.getElementById("demo");
x.innerHTML=children;
} //返回结果： Cecilie", "Lone","Emil", "Tobias", "Linus"
</script>

3.合并三个数组--concat()

<script>
var parents = ["Jani", "Tove"];
var brothers = ["Stale", "Kai Jim", "Borge"];
var children = ["Cecilie", "Lone"];
var family = parents.concat(brothers, children);
document.write(family);
</script>

4.用数组的元素组成字符串----join()

<script>
function myFunction()
{
var fruits = ["Banana", "Orange", "Apple", "Mango"];
var x=document.getElementById("demo");
x.innerHTML=fruits.join();
} //返回：Banana,Orange,Apple,Mango
</script>

5.删除数组的最后一个元素----pop()

<script>
var fruits = ["Banana", "Orange", "Apple", "Mango"];
function myFunction()
{
fruits.pop();
var x=document.getElementById("demo");
x.innerHTML=fruits;
}// 返回：Banana,Orange,Apple
</script>

6.数组末尾添加新的元素----push()

<script>
var fruits = ["Banana", "Orange", "Apple", "Mango"];
function myFunction()
{
fruits.push("Kiwi")
var x=document.getElementById("demo");
x.innerHTML=fruits;
}//返回Banana,Orange,Apple,Mango,Kiwi
</script>

7反转一个数组中元素的的顺序----reverse()

<script>
var fruits = ["Banana", "Orange", "Apple", "Mango"];
function myFunction()
{
fruits.reverse();
var x=document.getElementById("demo");
x.innerHTML=fruits;
}/.返回：Mango,Apple,Orange,Banana
</script>

8.删除数组中第一个元素---shift()

<script>
var fruits = ["Banana", "Orange", "Apple", "Mango"];
function myFunction()
{
fruits.shift();
var x=document.getElementById("demo");
x.innerHTML=fruits;
}//返回：Orange,Apple,Mango
</script>

9.从一个数组中选择元素--slice()

<script>
function myFunction()
{
var fruits = ["Banana", "Orange", "Lemon", "Apple", "Mango"];
var citrus = fruits.slice(1,4);
var x=document.getElementById("demo");
x.innerHTML=citrus;
}//返回：Orange,Lemon,Apple  注：由1开始到4结尾
</script>

10.数组排序（按字母顺序升序）--sort()

<script>
function myFunction()
{
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.sort();
var x=document.getElementById("demo");
x.innerHTML=fruits;
}//返回：Apple,Banana,Mango,Orange
</script>

11.数字排序（按数字顺序升序）---sort()

<script>
function myFunction()
{
var points = [40,100,1,5,25,10];
points.sort(function(a,b){return a-b});
var x=document.getElementById("demo");
x.innerHTML=points;
}//返回：1,5,10,25,40,100
</script>

12.数字排序（按数字顺序降序）---sort()

<script>
function myFunction()
{
var points = [40,100,1,5,25,10];
points.sort(function(a,b){return b-a});
var x=document.getElementById("demo");
x.innerHTML=points;
}//返回：100,40,25,10,5,1
</script>

13.在数组的第二个位置添加一个元素---splice()

解析：splice()用于插入、删除或替换元素

array.splice(index,howmany,item1,item2.......)

index:从何处添加/删除元素，该参数是开始位置元素的下标，必须是数字

howmany：应该删除多少数字，必须是数字，可以是0.若，没有规定此参数，

      则删除从index开始到数组结尾的所有元素

item1,item2.......：要添加到数组的所有元素

<script>
function myFunction()
{
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.splice(2,0,"Lemon","Kiwi");
var x=document.getElementById("demo");
x.innerHTML=fruits;
}//返回：Banana,Orange,Lemon,Kiwi,Apple,Mango
</script>

14.转化数组到字符串----toString（）

<script>
function myFunction()
{
var fruits = ["Banana", "Orange", "Apple", "Mango"];
var str = fruits.toString();
var x=document.getElementById("demo");
x.innerHTML= str;
}//返回：Banana,Orange,Apple,Mango
</script>

15在数组的开头添加新元素--unshift()

<script>
function myFunction()
{
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.unshift("Lemon","Pineapple");
var x=document.getElementById("demo");
x.innerHTML=fruits;
}
</script>

16.prototype：可以向对象添加属性和方法：

Array.prototype.myUcase=function()
{
  for (i=0;i<this.length;i++)
    {
    this[i]=this[i].toUpperCase();
    }
}

var fruits=["Banana","Orange","Apple","Mango"];
fruits.myUcase();//返回结果：BANANA,ORANGE,APPLE,MANGO

17.其他关于数组操作的方法：

indexOf():返回某个指定字符串值首次出现的位置，改方法从头到位搜索：

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

lastIndexOf():返回某个指定字符串最后出现的位置，在一个字符串中的指定位置从后向前搜索：

var fruits = ["Banana", "Orange", "Apple", "Mango"];
var a = fruits.lastIndexOf("Apple");//返回结果：2