Array and Array Methods

Array and Array Methods

What is an array?

The Array object, as with arrays in other programming languages, enables storing a collection of multiple items under a single variable name and has members for performing common array operations.

Creating Arrays

// empty array with no elements
var empty = [];   

// array with 2 string elements
var names = ["Ramesh", "Suresh"];   

// array with elements of different types
var mixed = [true, 100, "Namaste"];   

// 2 dimensional array with object literals
var array2 = [[1,{x:1, y:2}], [2, {x:3, y:4}]];  

// the 3rd element is undefined
var colors = ["Red", "Green", undefined];   

// no value in the 1st element, it is undefined
var hobbies = [,"Art"];

JavaScript Array Methods

Array methods are built-in functions that we can apply to our arrays. Each method has its own function that performs a specific operation on our array and returns or modifies the array accordingly.

length()

It determines the size of an array.

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];

console.log(names.length);        // => 4

push()

It inserts a new element at the end of the array.

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];
names.push("Teja");          //=>["Ramesh", "Suresh", "Pandu", "Muttu","Teja"]

unshift()

It inserts a new element at the beginning of the array.

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];
names.unshift("Teja");      //=>["Teja","Ramesh", "Suresh", "Pandu", "Muttu"]

pop()

Remove an element from the end of the array.

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];
names.pop();      //=>["Ramesh", "Suresh", "Pandu"]

shift()

Remove an element from the beginning of the array.

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];
names.shift();      //=>["Suresh", "Pandu", "Muttu"]

slice()

Create a shallow copy of an array.

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];
names.slice(2);      //=>["Pandu", "Muttu"]

splice()

This method can be used to insert, remove and replace elements. -It counts from 0 so it will skip the first element and continue to the last number you have given.

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];
names.splice(1,3);      //=>["Ramesh"] (Removed)

var names = ["Ramesh", "Suresh", "Pandu", "Muttu"];
names.splice(1,2,"Hello","Hi");      
//=>["Ramesh", "Hello", "Hi", "Muttu"] (Replaced)

There are many more array methods... I will update soon...