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JavaScript高级程序设计读书笔记之九本地对象Array

JavaScript对象 本地 高级 Array 程序设计 读书笔记
2023-06-13 09:14:32 时间
创建Array对象
复制代码代码如下:

//one
varaValues=newArray();

//two
varaValues=newArray(20);

//three
varaColors=newArray();
aColors[0]="red";
aColors[1]="green";
aColors[2]="blue";

//four
varaColors=newArray("red","green","blue");

//five
varaColors=["red","green","blue"];

join&&split
join:连接字符串
复制代码代码如下:

varaColors=["red","green","blue"];
alert(aColors.join(","));//outputs"red,green,blue"
alert(aColors.join("-"));//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:
varsColors="red,green,blue";
varaColors=sColors.split(",");//outputs["red","green","blue"]
varredColors=aColors[0].split("");//outputs["r","e","d"]

concat&&slice
concat:追加数组
复制代码代码如下:
varaColors=["red","green","blue"];
varaColors2=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:
varaColors=["red","green","blue","yellow","purple"];
varaColors2=aColors.slice(1);//outputs["green","blue","yellow","purple"]
varaColors3=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:
varstack=newArray;
stack.push("red");
stack.push("green");
stack.push("blue");
alert(stack);//outputs["red","green","blue"]
varvItem=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:
varaColors=["red","green","blue"];
varvItem=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:
varaColors=["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:
varaColors=[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:
varaColors=["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:
varaColors=["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:
varaColors=["red","green","blue","yellow"];
aColors.splice(2,1,"black","white");
alert(aColors);//outputs["red","green","black","white","yellow"]

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