JavaScript内置对象之Array

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Array对象为JavaScript内置的数组对象

一、Array对象的创建

1. 创建数组对象

var week = new Array(7);
var books = new Array();//可以不指定数组的长度

2. 初始化数组对象

var week = new Array("Sunday","Monday","Tuesday","Wednesday","Thursday","Friday","Saturday");
var test1 = [100,200,300];
var test2 = [100,"abcd",200];

3. 获取数组元素的个数：length 属性

4. 创建二维数组

var week = new Array(7);
for(var i = 0 ; i < 7 ;i ++){
    week[i] = new Array(2);
}
week[0][0] = "星期日";
week[0][1] = "Sunday";

week[1][0] = "星期一";
week[1][1] = "Monday";
...
week[6][0] = "星期六";
week[6][1] = "Saturday";

二、Array对象的常用方法

1. 数组转换为字符串

  - x.join([str]) ：str作为连接数组中元素的字符串，可省

  - x.toString() ：用“，”逗号连接数组成为字符串

var arr = [1,2,3,4];
alert(arr.join("<"));//1<2<3<4
alert(arr.toString());//1,2,3,4

2. 连接数组

  - x.concat(value,....) ：value 作为数组元素连接到数组的末尾

var a = [1,2,3];
var b = a.concat(4,5,6,7);
alert(a.toString());//1,2,3
alert(b.toString());//1,2,3,4,5,6,7

3. 获取子数组

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  - x.slice(start,[end]) ：start位置开始索引；end为结束位置加1，省略则从start位置截取以后数组的所有元素。

var arr1 = ['a','b','c','d','e','f'];
var arr2 = arr1.slice(2,5);
alert(arr2.toString());//c,d,e
var arr3 = arr1.slice(2);
alert(arr3.toString());//c,d,e,f

4.数组反向与排序

  - x.reverse() ：反向数组，改变数组中数值的顺序

var arr1 = [12,23,34,45,56];
alert(arr1.reverse().toString());//56,45,34,23,12

  - x.sort([sortFunction]) ：数组排序，sortFunction ：可选项，用来确定元素顺序的函数的名称

var arr = [12,2,4536,23];
alert(arr.sort().toString());//12,2,4536,23
alert(arr.sort(sortFunction).toString());//2,12,23,4536
function sortFunction(a,b){
    return a-b;
}