首页 / 脚本样式 / JavaScript / JavaScript高级程序设计 读书笔记之九 本地对象Array

创建Array对象
复制代码 代码如下:
//one
var aValues=new Array（）;

//two
var aValues=new Array（20）;

//three
var aColors=new Array（）;
aColors[0]="red";
aColors[1]="green";
aColors[2]="blue";

//four
var aColors=new Array（"red","green","blue"）;

//five
var aColors=["red","green","blue"];

join && split
join:连接字符串
复制代码 代码如下:
var aColors=["red","green","blue"];
alert（aColors.join（","））;//outputs "red,green,blue"
alert（aColors.join（"-spring-"））;//outputs "red-spring-green-spring-blue"
alert（aColors.join（"]["））;//outputs "red][green][blue"

split:分拆字符串
复制代码 代码如下:
var sColors="red,green,blue";
var aColors=sColors.split（","）;//outputs ["red", "green", "blue"]
var redColors=aColors[0].split（""）;//outputs ["r", "e", "d"]

concat && slice
concat:追加数组
复制代码 代码如下:
var aColors=["red","green","blue"];
var aColors2=aColors.concat（"yellow","purple"）;
alert（aColors）;//outputs ["red", "green", "blue"]
alert（aColors2）;//outputs ["red", "green", "blue", "yellow", "purple"]

slice:返回具有特定项的新数组
复制代码 代码如下:
var aColors=["red","green","blue","yellow","purple"];
var aColors2=aColors.slice（1）;//outputs ["green","blue","yellow","purple"]
var aColors3=aColors.slice（1,4）;//outputs ["green","blue","yellow"]

push && pop
跟栈一样，Array提供了push和pop方法，push方法用于在Array结尾添加一个或多个项，pop用于删除最后一个数组项，返回它作为函数值
复制代码 代码如下:
var stack=new Array;
stack.push（"red"）;
stack.push（"green"）;
stack.push（"blue"）;
alert（stack）;//outputs ["red","green","blue"]
var vItem=stack.pop（）;
alert（vItem）;//outputs ["blue"]
alert（stack）;//otputs ["red","green"]

shift && unshift
shift:删除数组中第一项，将其作为函数返回值，unshift:把一个项放在数组的第一个位置，然后把余下的项向下移动一个位置
复制代码 代码如下:
var aColors=["red","green","blue"];
var vItem=aColors.shift（）;
alert（aColors）;//outputs ["green","blue"]
alert（vItem）;//outputs ["red"]
aColors.unshift（"black"）;
alert（aColors）;//outputs ["black","green","blue"]

reverse && sort
reverse:颠倒数组项的顺序，sort:按数组项的值升序排列（首先要调用toString（）方法，将所有值转换成字符串）
复制代码 代码如下:
var aColors=["blue","green","red"];
aColors.reverse（）;
alert（aColors）;//outputs ["red","green","blue"]
aColors.sort（）;
alert（aColors）;//outputs ["blue","green","red"]

注意：
复制代码 代码如下:
var aColors=[3,32,2,5];
aColors.sort（）;
alert（aColors）;//outputs [2,3,32,5]

这是因为数字被转换成字符串，然后按字符代码进行比较的。

splice
splice:把数据项插入数组的中部

1、用作删除：只要声明两个参数，第一个参数为要删除的第一个项的位置，第二个参数为删除项的个数
复制代码 代码如下:
var aColors=["red","green","blue","yellow"];
aColors.splice（0,2）;
alert（aColors）;//outputs ["blue", "yellow"]

2、用作插入：声明三个或以上参数（第二个参数为0）就可以把数据插入指定位置，第一个参数为地始位置，第二个参数为0，第三个及以上参数为插入项
复制代码 代码如下:
var aColors=["red","green","blue","yellow"];
aColors.splice（2,0,"black","white"）;
alert（aColors）;//outputs ["red","green","black","white","blue", "yellow"]

3、用作删除并插入：声明三个或以上参数（第二个参数为不0）就可以把数据插入指定位置，第一个参数为地始位置，第二个参数为要删除的项的个数，第三个及以上参数为插入项
复制代码 代码如下:
var aColors=["red","green","blue","yellow"];
aColors.splice（2,1,"black","white"）;
alert（aColors）;//outputs ["red","green","black","white", "yellow"]