Array对象常用方法

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//shift:删除原数组的第一项，返回删除元素的值；如果数组为空则返回undefined

var arr = [1, 2, 3, 4, 5];

var out = arr.shift();

console.log(arr); //[2,3,4,5]

console.log(out); //1

var arr = [];

var out = arr.shift();

console.log(arr); //[]

console.log(out); //undefined

//unshift:将参数添加到原数组开头，返回数组的长度(ie6下返回undefined)

var arr = [1, 2];

var out = arr.unshift(-1, 0);

console.log(arr); //[-1,0,1,2]

console.log(out); //4

//pop:删除原数组的最后一项，返回数组删除的值；如果数组为空则返回undefined

var arr = [1, 2, 3, 4, 5];

var out = arr.pop();

console.log(arr); //[1,2,3,4]

console.log(out); //5

var arr = [];

var out = arr.pop();

console.log(arr); //[]

console.log(out); //undefined

//push:将参数添加到原数组的末尾，返回数组的长度

var arr = [1, 2, 3];

var out = arr.push(4, 5, 6);

console.log(arr); //[1,2,3,4,5,6]

console.log(out); //6

//concat:返回一个将参数添加到原数组中构成的新数组

var arr = [1, 2, 3];

var out = arr.concat(4, 5);

console.log(arr); //[1,2,3]

console.log(out); //[1,2,3,4,5]

//splice(start,deleteCount,val1,val2,...):从start位置开始删除原数组deleteCount项，并从该位置起插入val1,val2,...，返回删除的项组成的新数组

var arr = [1, 2, 3, 4, 5];

var out = arr.splice(2, 2, 7, 8, 9, 10);

console.log(arr); //[1,2,7,8,9,10,5]

console.log(out); //[3,4]

//在清空数组时仅需传递start，如果不删除所有元素，再传递deleteCount

var arr = [1, 2, 3, 4, 5];

var out = arr.splice(2);

console.log(arr); //[1,2]

console.log(out); //[3,4,5]

//同shift

var arr = [1, 2, 3, 4, 5];

var out = arr.splice(0, 1);

console.log(arr); //[2,3,4,5]

console.log(out); //[1]

//同unshift

var arr = [1, 2, 3, 4, 5];

var out = arr.splice(0, 0, 22, -1, 0);

console.log(arr); //[22,-1,0,1,2,3,4,5]

console.log(out); //[]

//同pop

var arr = [1, 2, 3, 4, 5];

var out = arr.splice(arr.length - 1, 1);

console.log(arr); //[1,2,3,4]

console.log(out); //[5]

//同push

var arr = [1, 2, 3, 4, 5];

var out = arr.splice(arr.length, 0, 6, 7, 8);

console.log(arr); //[1,2,3,4,5,6,7,8]

console.log(out); //[]

//reverse:将原数组倒序；

var arr = ['a', 1, {}, [2, 3]];

console.log(arr); //['a', 1, {}, [2, 3]]

var out = arr.reverse();

console.log(arr); //[[2,3],{},1,'a']

console.log(out); //[[2,3],{},1,'a']

var arr = [0, 1, 5, 10, 15];

arr.reverse();

console.log(arr); //[15,10,5,1,0]

var arr = [1, 0, 5, 15, 10];

arr.reverse();

console.log(arr); //[10,15,5,0,1]

//sort(orderfunction):sort()为升序排列，但是先调用每个数组项的toString()方法，然后比较字符串来排序，是按ASCII进行比较的；

//所以跟reverse不同原理不同。sort()不带参数的时候是从字面上对数组排序

var arr = [0, 1, 5, 10, 15];

arr.sort();

console.log(arr); //0,1,10,15,5 ,注意这里是字符串按ASCII进行比较的

//调用这样的函数就按数值方式排列了

function sortNumber(a, b) {

return a - b

}

arr.sort(sortNumber);

console.log(arr); //0,1,5,10,15

//slice(start,end):返回从原数组中指定start到end(不包含该元素)之间的项组成的新数组,如只有一个参数，则从start到数组末尾

var arr = [1, 2, 3, 4, 5, 6, 7, 8];

var out = arr.slice(2,3);

console.log(arr); //[1, 2, 3, 4, 5, 6, 7, 8]

console.log(out); //[3]

//join(separator):将数组的元素组成一个字符串，以separator为分隔符，省略的话则用默认用逗号为分隔符

var arr = [1, 2, 3, 4, 5, 6];

var out = arr.join();

console.log(arr); //[1, 2, 3, 4, 5, 6]

console.log(out); //1,2,3,4,5,6

out = arr.join("");

console.log(out); //123456

out = arr.join("&");

console.log(out); //1&2&3&4&5&6

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/** 删除数组中指定索引的数据 **/

Array.prototype.deleteAt = function (index) {

if (index< 0) {

return this;

}

return this.slice(0, index).concat(this.slice(index + 1,this.length));

}

/** 数组洗牌 **/

Array.prototype.random = function () {

var tempArr =[], me = this, t;

while (me.length> 0) {

t = Math.floor(Math.random() * me.length);

tempArr[tempArr.length] = me[t];

me =me.deleteAt(t);

}

return tempArr;

}

Array.prototype.orderRandom = function () {

return this.sort(function () {

return Math.random() > 0.5 ? "-1" : "1";

});

}

/** 数字数组排序 **/

Array.prototype.sortNum = function (i) {

if (!i) {

i = 0;

}

if (i == 1) {

return this.sort(function (a, b) {

return b - a;

});

}

return this.sort(function (a, b) {

return a - b;

});

}

/** 获取数字数组中的最大项 **/

Array.prototype.getMax = function () {

return this.sortNum(1)[0];

}

/** 获取数字数组中的最小项 **/

Array.prototype.getMin = function () {

return this.sortNum(0)[0];

}

/** 数组第一次出现指定元素的位置 **/

Array.prototype.indexOf = function (o) {

for (var i = 0; i <this.length;i++) {

if (this[i] == o) {

return i;

}

return -1;

}

/** 去除数组中的重复项 **/

Array.prototype.arrUnique = function () {

var reset =[], done = {};

for (var i = 0; i <this.length;i++) {

var temp = this[i];

if (!done[temp]) {

done[temp] = true;

reset.push(temp);

}

return reset;

}

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