JS

Array in Javascript

1.Create an Array.

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/** Create an array **/
var arrayObj = new Array();
arrayObj[0] = "obj1";
arrayObj[1] = "obj2";
arrayObj[2] = "obj3";

/** Create an array and specify(initial length) length,
 *  but the actual length can be more than 3
**/
var arrayObj = new Array(3);
arrayObj[0] = "obj1";
arrayObj[1] = "obj2";
arrayObj[2] = "obj3";

/** Create an array and assign values **/
var arrayObj = new Array("ojb1", "obj2", "obj3");

/** Simply you can do as this **/
var arrayObj = ["obj1", "obj2", "obj3"];

2.Access values

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var arrValue = arrayObj[1]; // get the value
arrayObj[1] = "newValue"; //assign a new value

3.Add items to an Array

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//Add one or more items to the end of the array, return the array length
arrayObj.push("newObj1", "newObj2");

//Add one or more items to the beginning of the array, return the array length
arrayObj.unshift("newObj1", "newObj2");

//At position 2, remove 2 items, and add "newObj1", "newObj2" to the end of the array
arrayObj.splice(2, 2, "newObj1", "newObj2");

4.Delete items from an Array

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//remove the last item of an array and return this item
arrayObj.pop();

//remove the first item of an array and return this item
arrayObj.shift();

//delete numbers of items from the specified position
arrayObj.splice(deletePos, deleteCounts);

5.Select items from an array or join two or more arrays

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//select items from position start to end as a new array and return it.
//end can be empty
arrayObj.slice(start, end);

//join several arrays
arrayObj.concat(array1, array2, array3);

6.Copy an array

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arrayObj.slice(0); //return a new copy of the array
arrayObj.concat(); //return a new copy of the array

7.Sort an array

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arrayObj.reverse(); //return the reverse of an array
arrayObj.sort();
var fruits = ["Banana", "Orange", "Apple", "Mango"];
fruits.sort(); //result:Apple,Banana,Mango,Orange

var points = [40,100,1,5,25,10];
points.sort(function(a,b){return a-b}); //result: 1,5,10,25,40,100

8.Array to string

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arrayObj.join(separator); //joint the items of an array with separator