In this particular post I will write all the comments in inside the code. It will be easy to have all the functions in a single location so that you can go through all the topics all at once.

//
// Declaring an Array
var myArray = new Array(); // Using Array Constructor, try to avoid this
var myArray = Array(); // not preferred
var myArray = []; // Using Array literal, always use this.

// Declaring and initialising 
var myArray = new Array(element1,element2,element3);
var myArray = Array(element1,element2,element3);
var myArray = [element1,element2,element3]; // preferred array
var anotherArray=[3,4,"first String",9,{element1:"another string"}] // array with mixed type element

var myArray = new Array(10,20) // create an array with 2 elements
var myArray = new Array(20) // create an array with 20 undefined elements

var myArray = Array(10,20) // create an array with 2 elements
var myArray = Array(20) // create an array with 20 undefined elements

var myArray = [];
myArray.Length = 20 // create an array with 20 undefined elements

//

Methods of Array

Array has a number of methods that help us to do operation in an array easily.

concat() method

concat() joins two or more arrays and returns a new array. Instead of joining two or multiple arrays you can even add a new elements with a single array.

//
var array1 = [1,2,3];
var array2 = [4,5,6];
var array3 = [7,8,9];

console.log(array1) // output [1,2,3]

// joining multiple array
array1 = array1.concat(array2,array3);
console.log(array1) // output [1,2,3,4,5,6,7,8,9]

// adding array elements with an existing array
array1 = array1.concat(10,11);
console.log(array1) // output [1,2,3,4,5,6,7,8,9,10,11]
//

Converting an array to a string, join() and toString() method

If you want to convert an array to a string there are two predefined methods.

join() method

Join() method you can specify a separator.If you do not use any separator than it will use comma “,” as default separator.

//
var array1 = ["apple","banana"];
console.log(array1.join()); // will print apple,banana
console.log(array1.join("-")); // will print apple-banana
//

toString() method

You can convert an array to comma separated string by using toString() method. You can not change your separator in toString() method. It will be always a comma “,”.

//
var array1 = ["apple","banana"];
console.log(array1.toString()); // will print apple,banana
console.log(array1.toString("-")); // will print print apple,banana
//

Adding or removing elements from an array push(), pop(), shift(), unshift()

You can add a new element or remove an existing element from an array in a number of ways. Based upon your logic you can use any of them.

push()

Push method add an element at the end of the array.

//
var array1 = [1,2];
array1.push(3); // will add 3 at the end of the array
console.log(array1); // will print [1,2,3]
//

pop()

Pop method removes the last element from an array and return that element.

//
var array1 = [1,2,3];
var last = array1.pop(); // remove the last element from an array
console.log(last); //will print 3
console.log(array1); // will print [1,2]
//

shift()

Shift() method removes the first element from an array and returns that element.

//
var array1 = [1,2,3];
var removedElement = array1.shift(); // will add 3 at the end of the array
console.log(array1); // will print 2,3]
console.log(removedElement);// will print 1
//

unshift()

unshift() method adds new elements at the beginning of the array.

//
var array1 = [1,2,3];
array1.unshift(4,5);
console.log(array1); // will print [4,5,1,2,3]
//

In short, if you want to add new elements with an array you can use either push() or unshift() methods.
On the other hand if you want to remove elements from an array then you can use either pop() or shift() method.

• push() method add new elements at the end of the array.
• unshift() method add new elements at the beginning of the array.
• pop() method remove an element from the end of the array and returns that element.
• shift() method remove an element from the beginning of the array.

//
//