JS对象 - Array属性方法汇总

摘要：属性名描述为对象添加属性方法返回数组对象引用返回数组元素数目方法名描述返回更改原数组连接多个数组连接后新数组将数组中所有元素合为一个字符串。

new Array();
new Array(size);
new Array(element0, element1, ..., elementn);
var arr = []; //字面量方式

经测试用字面量方式跟new Array()耗时差不多，使用习惯的差距吧~ new Array()能初始化长度~

prototype 向对象添加属性和方法

function em(A,B)
{
    this.A = A;
    this.B = B;
}
var e = new em("AA","BB");
em.prototype.C = null;
e.C = 20000;
console.log(e.C); //20000
console.log(e); //em {A:"AA" , B:"BB" , C : 20000 }

constructor 返回对创建此对象的数组函数的引用

function employee(name,job)
{
    this.name = name;
    this.job = job;
}
var bill = new employee("Bill");
console.log(typeof bill.constructor); // function
console.log(bill.constructor); //function employee(name){this.name=name;this.job=job;}

concat() 连接两个或更多的数组（返回被连接数组的副本）

var arr = [1, 2, 3];
var arr1 = [6, 7];
console.log(arr.concat(4, 5, arr1)); //[1, 2, 3, 4, 5, 6, 7]

join() 把数组的所有元素放入一个字符串，元素通过指定的分隔符分隔。

var arr = ["item 1", "item 2", "item 3"];
var list = "
" + arr.join("
") + "
"; //"
item 1
item 2
item 3
"

toString() 数组转换为字符串（与无参的 join()方法返回的串相同）

var arr = new Array(3)
arr[0] = "A"
arr[1] = "B"
arr[2] = "C"
console.log(arr.toString()); //"A,B,C"

pop() 删除数组的最后一个元素，数组长度减 1，并返回被删除的元素的值

若数组为空，则pop()返回undefined值

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.pop()); //"C"
console.log(arr); //["A", "B"]

push() 向数组的末尾添加一个或更多元素，并返回新的长度

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.push("D")); //4
console.log(arr); ////["A", "B", "C" , "D"]

reverse() 颠倒数组中元素的顺序

var arr = ["A", "B", "C"];
arr.reverse();
console.log(arr);// ["C", "B", "A"]

slice(start,end) 从数组中返回选定的子数组

var arr = ["A", "B", "C"];
// 从第一个元素开始截取到数组结尾
console.log(arr.slice(1)); //["B", "C"]
console.log(arr); //["A", "B", "C"]

splice() 删除元素，并向数组添加新元素
(直接对数组操作)

① 删除指定范围的数组元素：

var arr = new Array(6);
    arr[0] = "A"; 
    arr[1] = "B";
    arr[2] = "C";
    arr[3] = "D";
    arr[4] = "E";
    arr[5] = "F";
console.log(arr); //["A", "B", "C", "D", "E", "F"]
// 删除第三个元素以后的三个数组元素(包含第三个元素)
console.log(arr.splice(2, 3));  //["C", "D", "E"]
console.log(arr); //["A", "B", "F"]

② 从指定下标开始插入指定元素(元素个数不限)：

    var arr = new Array(6);
    arr[0] = "A"; 
    arr[1] = "B";
    arr[2] = "C";
    arr[3] = "D";
    arr[4] = "E";
    arr[5] = "F";
console.log(arr); //["A", "B", "C", "D", "E", "F"]
console.log(arr.splice(2, 0, "AA","BB")); // []
console.log(arr);//["A", "B", "AA" , "BB" , "C", "D", "E", "F"]

③ 删除指定范围的数组元素，并用指定元素替换(元素个数不限)：

var arr = new Array(6);
    arr[0] = "A"; 
    arr[1] = "B";
    arr[2] = "C";
    arr[3] = "D";
    arr[4] = "E";
    arr[5] = "F";
console.log(arr);//["A", "B", "C", "D", "E", "F"]
console.log(arr.splice(2, 1, "AA","BB")); // ["C"]
console.log(arr); //["A", "B", "AA", "BB", "D", "E", "F"]

sort() 对数组的元素进行排序
对数组的引用

数组在原数组上进行排序，不生成副本。该方法默认是按照字符编码(ASCII)的顺序进行排序的

var arr = new Array(3);
    arr[0] = "D";
    arr[1] = "S";
    arr[2] = "A";
console.log(arr); //["D", "S", "A"]
console.log(arr.sort()); //["A", "D", "S"]

自行指定排序规则。如下：

var arr = new Array(6);
    arr[0] = 10;
    arr[1] = 5;
    arr[2] = 40;
    arr[3] = 25;
    arr[4] = 1000;
    arr[5] = 1;
console.log(arr); //[10, 5, 40, 25, 1000, 1]
//升序
console.log(arr.sort(function (a, b) {return a - b;}));// [1, 5, 10, 25, 40, 1000]

valueOf() 返回相应的原始值

var arr = new Array(2);
    arr[0] = 10
    arr[1] = 5
console.log(arr); //[10, 5]
console.log(typeof arr.valueOf()); //object
console.log(arr.valueOf()); //[10, 5]

shift() 删除并返回数组的第一个元素

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.shift()); //A
console.log(arr); //["B", "C"]

unshift() 向数组的开头添加一个或更多元素，并返回新的长度

var arr = ["A", "B", "C"];
console.log(arr); //["A", "B", "C"]
console.log(arr.unshift("AA")); //4
console.log(arr);//["AA", "A", "B", "C"]

indexOf() 返回元素在数组中出现位置

额 之前一直以为只有string有这个方法... 补上补上

var arr = ["orange", "2016", undefined , null ,NaN];
console.log(arr.indexOf("orange")); //0
console.log(arr.indexOf("o")); //-1
console.log(arr.indexOf("2016"));  //1
console.log(arr.indexOf(2016));  //-1
console.log(arr.indexOf("undefined"));  //-1
console.log(arr.indexOf(null));  //3
console.log(arr.indexOf(NaN));  //-1

以上只是为了论证这里的indexOf使用的是严格匹配（===），不会像string的indexOf一样隐式转换成字符串进行匹配~