Java Script: Array Reference

Array

Arrays are a way of storing multiple values together.
Arrays are best use to store similar values.

Creating Array

var myArray = [];

var myArray = new Array(Number of Element);

var myArray = new Array(Element 1, Element 2,...);

Looping Array

Easiest way to access all elements.

var myArray = [1,2,3]; 

for(var index in myArray){

     document.write(myArray[index]);

}

Result

123

Traditional programming approach. Can only access contiguous array.

var myArray = [1,2,3]; 

for(var index=0; index < myArray.length; index++){

     document.write(myArray[index]);

}

Result

123

Looping through the array and consuming it contents. Starting with the last element

var myArray = [1,2,3]; 
while(myArray.length){
     document.write(myArray.pop());
}

Result

321

Looping through the array and consuming it contents. Starting from the first element

var myArray = [1,2,3]; 
while(myArray.length){
     document.write(myArray.shift());
}

Result

123

Other Cool methods

array.concat(array[,array]*) 

Join two or more array and return the joined array.
Example

var myArrayA = [1,3,5];

var myArrayB = ['a','b','c'];

var combineArray = myArrayA.concat(myArrayB);

Result

myArrayA = [1,3,5]
myArrayB = ['a','b','c'];
combineArray = [1,3,5,'a','b','c'];

array.join()

concatenate all element of an array into a string.

Example

var myArray = ['a','b','c'];
var myString = myArray.join();

Result

myArray = ['a','b','c'];
myString = "abc";

array.pop()

remove the last element of the array.

array.push()

insert an element to the end of the array;

array.shift()

remove the first element of the array.

array.unshift()

insert an element at the beginning of the array.

Example

var myArray = ['a','b','c','d','e'];
var myPop = myArray.pop();
var myShift = myArray.shift();
myArray.unshift(myPop);
myArray.push(myShift);

Result

myArray = ['e','b','c','d','a'];
myPop = 'e'
myShift = 'a'

array.reverse() 

Reverses the order of the elements in the array

Example

var myArray = ['a','b','c','d','e'];
myArray.reverse();

Result

myArray = ['e','d','c','b','a'];

array.slice(start, end)

Create an array from a part of the current array. Beginning at start and end at end.

array.splice(index, element to remove [, new element]*);

remove number of element at position index, and insert new element at index. Returning removed elements.

Example

var myArray = ['a','b','c','d','e'];
var mySliceArray = myArray.slice(1,3);
var myRemoveElement = myArray.splice(1,3,'z','y');

Result

myArray = ['a','z','y','e']
mySliceArray = ['b','c'];
myRemoveElement = ['b','c','d'];

array.sort(function(a,b){return a>b}?)

Sort the array by the provided function.
The default comparison function is function(a,b){return a>b}.

Example

var myArray = [4,3,1,2];
myArray.sort();

Result

myArray = [1,2,3,4];