JavaScript Array Learning

Record the process of learning an array 1, creating an array

1 var New Array (); // Empty Array 2 var ary2= []; // literal quantity

2. Array detection

// Method One if instanceof Array) {}// method Two ES5if(Array.isarray (Array)) {}//  Object.prototype.toString.apply (arrary,arguments);

3. Array conversion method

//1, toString ();        varary =[' aaaa ', ' VVVVV ']; Ary.tostring ();//"AAAA,VVVVV"//2, ValueOf ();    varary =[' green ', ' blue ', ' red ']; Ary.valueof ();//["Green", "Blue", "Red"]//3, toLocaleString ();Ary.tolocalestring ();//"Green,blue,red"//4, join ();Ary.join (' @@@&&&&&***** ')//"[Email protected]@@&&&&&*****[email protected]@@&&&&&*****red"

4. Find a Way

' Last in first out ' performance

ary =[' AA ', ' BBB ', ' cccc ', ' dddd ']; // ["AA", "BBB", "CCCC", "dddd"] Ary.pop (); // "dddd"ary.push (' dddd '); // 4 ary // ["AA", "BBB", "CCCC", "dddd"]

5. Queue method

The performance of ' FIFO '

var ary = ["AA", "BBB", "CCCC", "dddd"];ary.shift (); // "AA"ary.unshift (' aaaaaaaaaaaa '); // 4console.log (ary); // ["Aaaaaaaaaaaa", "BBB", "CCCC", "dddd"]

6. Loop Array (scroll selection)

1, from the back to the front

var ary =[10,20,30,40,50,60,70,80,90]; // from the back to the front // 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. From the front to the back

 for (var i = 0, Len =ary.length; i<len;i++) {    console.log (ary);    Ary.push (Ary.shift ());    Console.log (ary);}

7. Array sorting

var ary =[90,100,90,33300,10,20,30,40,50,60,70,80,90];ary.sort (function(val1,val2 ) {    return val1-val2;}); // [Ten, +, +,--]----------------33300] Ary.sort (function(val1,val2)    {
   
    return val2-
    val1;}); 
    // 
    [33300, +,------------
   

8. Array method

1, concat ();

Ary.concat (' AAA ', [' ddd ', ' CCC ', ' eeee '); // [33300, +,------------------------

2, slice ();

var ary1 = [33300, +,-------------------------- /c4>0,5); // [33300,N, Console.log (ary1); // [33300,------------------------------- // [+]

3, splice (); The most powerful method

varAry2 = [' 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. Position method (ES5)

Ary1 = [' 222 ', ' ffff ', ' sfff ', ' a ']//["222", "FFFF", "Sfff", "a"]ary1.indexof (' a '); // 3ary1.indexof (' aaaaa '); // -1

10. Array method in ES5 (iterative method)

1.every (); Returns true for all values in the array

2.some (); Returns true if the array

3.forEach (); the array each run function, no return value

4.map (); Every item in an array runs a function that returns an array

5.filter (); An array of each run function that returns an array of ture

varAry1 = [10,20,5,44,444];ary1.some (function(value,index) {returnvalue>100;});//tureAry1.every (function(value) {returnValue<0;});//falseAry1.map (function(value,index) {returnValue+index;});//[Ten, 7, 448]Ary1.filter (function(value,index) {returnValue>40;});//[444]Ary1.foreach (function(Value,index) {Ary1[index]=value*2;}); Console.log (ary1);//[+, 888]

JavaScript Array Learning