Javascript数组学习

　　记录下学习数组的过程

　　1、创建数组

 var ary1 = new Array();//空数组

 var ary2= [] ;//字面量

　　2、数组检测

//方法一

if(array instanceof Array){

}

//方法二 ES5

if(Array.isArray(array)){

}

//方法三

Object.prototype.toString.apply(arrary,arguments);

　　3、数组转换方法

//1、toString();

        var ary =['aaaa','vvvvv'];

        ary.toString();//"aaaa,vvvvv"

//2、valueOf();

    var ary =['green','blue','red'];

        ary.valueOf();//["green", "blue", "red"]

//3、toLocaleString();

ary.toLocaleString();//"green,blue,red"

//4、join();

ary.join('@@@&&&&&*****')

//"green@@@&&&&&*****blue@@@&&&&&*****red"

　　4、找方法

　　‘后进先出’的表现

ary =['aa','bbb','cccc','dddd'];

//["aa", "bbb", "cccc", "dddd"]

ary.pop();

//"dddd"

ary.push('dddd');

//

ary

//["aa", "bbb", "cccc", "dddd"]

　　5、队列方法

　　‘先进先出’的表现

var ary = ["aa", "bbb", "cccc", "dddd"];

ary.shift();//"aa"

ary.unshift('aaaaaaaaaaaa');//

console.log(ary);//["aaaaaaaaaaaa", "bbb", "cccc", "dddd"]

　　6、循环数组（滚动选择）

1、从后到前

var ary =[10,20,30,40,50,60,70,80,90];

//从后到前

//ary.unshift(ary.pop());

for(var i = 0 ,len =ary.length; i<len;i++){

    console.log(ary);

    ary.unshift(ary.pop());

    console.log(ary);

}

2、从前到后

for(var i = 0 ,len =ary.length; i<len;i++){

    console.log(ary);

    ary.push(ary.shift());

    console.log(ary);

}

　　7、数组排序

var ary =[90,100,90,33300,10,20,30,40,50,60,70,80,90];

ary.sort(function(val1,val2){

    return val1-val2;

});

//[10, 20, 30, 40, 50, 60, 70, 80, 90, 90, 90, 100, 33300]

ary.sort(function(val1,val2){

    return val2-val1;

});

//[33300, 100, 90, 90, 90, 80, 70, 60, 50, 40, 30, 20, 10]

　　8、数组方法

1、concat();

ary.concat('aaa',['ddd','ccc','eeee']);

//[33300, 100, 90, 90, 90, 80, 70, 60, 50, 40, 30, 20, 10, "aaa", "ddd", "ccc", "eeee"]

2、slice();

var ary1 = [33300, 100, 90, 90, 90, 80, 70, 60, 50, 40, 30, 20, 10, "aaa", "ddd", "ccc", "eeee"];

ary1.slice(0,5);//[33300, 100, 90, 90, 90]

console.log(ary1);//[33300, 100, 90, 90, 90, 80, 70, 60, 50, 40, 30, 20, 10, "aaa", "ddd", "ccc", "eeee"]

ary1.slice(1,3);//[100, 90]

3、splice();最强大的方法

var ary2 = ['a','b','c','d','e','aa','bb','cc']

ary2

//["a", "b", "c", "d", "e", "aa", "bb", "cc"]

ary2.splice(0,0);

//[]

ary2

//["a", "b", "c", "d", "e", "aa", "bb", "cc"]

ary2.splice(1,3);

//["b", "c", "d"]

ary2

//["a", "e", "aa", "bb", "cc"]

ary2.splice(0,0,'a','aaaa');

//[]

ary2

//["a", "aaaa", "a", "e", "aa", "bb", "cc"]

　　　9、位置方法(ES5)

ary1 = ['222','ffff','sfff','a']

//["222", "ffff", "sfff", "a"]

ary1.indexOf('a');

//

ary1.indexOf('aaaaa');

//-1

　　10、ES5中数组方法（迭代方法）

1.every();数组所有值返回true 返回true

2.some();数组其中有返回true 返回true

3.forEach();数组每一项运行函数，没有返回值

4.map();数组每一项运行函数，返回数组

5.filter();数组每一项运行函数，返回 ture数组

var ary1 = [10,20,5,44,444];

ary1.some(function(value,index){

    return value>100;

});//ture

ary1.every(function(value){

    return value<0;

});//false

ary1.map(function(value,index){

    return value+index;

});//[10, 21, 7, 47, 448]

ary1.filter(function(value,index){

    return value>40;

});//[44, 444]

ary1.forEach(function(value,index){

    ary1[index]=value*2;

});

console.log(ary1);//[20, 40, 10, 88, 888]

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