Everything You Need to Know About JavaScript Array Methods

Web development or web programming gave birth to dynamic web applications. With the rise of the web, JavaScript has become one of the most important languages in today’s world. This JavaScript Array article will take you to the depths of array methods in JavaScript in the following sequence:

Introduction to JavaScript

JavaScript is a high level, interpreted, programming language used to make web pages more interactive. It is a very powerful client-side scripting language which makes your webpage more lively and interactive.

It is a programming language that helps you to implement a complex and beautiful design on web pages. If you want your web page to look alive and do a lot more than just gawk at you, JavaScript is a must.

Fundamentals of JavaScript

If you are new to the language, you need to know some of the fundamentals of JavaScript that will help you start writing your code. The basics include:

• Variables
• Constants
• Data Types
• Objects
• Arrays
• Functions
• Conditional Statements
• Loops
• Switch case

You can check out the JavaScript Tutorial to get into the depth of these basic concepts and fundamentals of JavaScript. In this JavaScript Array article, we will focus on the different array methods used to define a list of items.

Related Learning: JavaScript Interview Questions

JavaScript Array

An array is a data structure that contains a list of elements which store multiple values under a single variable.

To declare an array in JavaScript use the ‘let’ keyword with square brackets and enclose all the elements within them. The syntax is as follows:

let ListItems=[];
ListItems=['shoes','watch','bag'];

You can also declare it as:

let ListItems=['shoes','watch','bag'];

Difference between Array and Objects

JavaScript variables can be objects. Arrays are considered to be special kinds of objects. Because of this, you can have variables of different types in the same Array.

myArray[0] = Date.now;
myArray[1] = myFunction;
myArray[2] = myItems;

In JavaScript, arrays use numbered indexes. Whereas, objects are used as named indexes.

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JavaScript Array Methods

The purpose of using an array is to store multiple values in a single entity of a declared variable. Arrays are used when we want to access elements in an orderly fashion using a single variable. One can store strings, boolean and numbers in a single array.

There are different JavaScript array methods in order to perform various tasks such as:

• push() – It is easy to remove elements and add new elements while working with arrays. The push() method adds a new element to the end of an array. The return value is the new array length.

Example:

let listItems = ['bag','shoes','dress'];
console.log(listItems.push('watch'));

Output:

4

Push() doest not return the value that has been added to the array. It only returns the new length of the array.

• pop() – The pop() method is used to remove the last element from an array. It returns the value that has been popped out.

Example:

let listItems = ['bag','shoes','dress'];
console.log(listItems.pop());

Output:

dress

Pop() returns the value that has been removed and not the array length like Push().

• shift() – Shifting is similar to popping, working on the first element instead of the last. The shift() method is used to remove the first array element and shifts all other elements to a lower index. It will return you the string that has been shifted out.

Example:

let listItems = ['bag','shoes','dress'];
console.log(listItems.shift());

Output:

bag

Shift() works same as pop() but it returns the first element of the array instead of the last one.

• unshift() – The unshift() method adds a new element at the beginning of an array and unshifts older elements. It is similar to Push() and returns the new array length.

Example: 

let listItems = ['bag','shoes','dress','watch'];
console.log(listItems.unshift('phone'));

Output:

5

Unshift() will add the new element into the array and return the length of the new array.

• concat() – The concat() method creates a new array by concatenating or merging existing arrays. It does not modify the existing array and always returns a new array.

Example:

let arr1 = ['red','blue','green'];
let arr2 = ['colors','spraypaint', 'brush'];
let newArr = arr1.concat(arr2);
console.log(newArr);

Output:

• toString() – The toString() method is used to convert an array to a string of array values, separated by commas.

Example:

let colors = ['red','blue','green'];
console.log(colors.toString());

Output:

red,blue,green

• join() – The join() method works same as toString(). It is used to join all array elements into a string, but in addition, you can specify the separator.

Example:

let colors = ['red','blue','green'];
console.log(colors.join("+"));

Output:

red+blue+green

• reverse() – The reverse() method is used to reverse the order of the elements in an array. It will change the original array and swap the order of the elements.

Example:

let fruits = ['mango','apple','grapes'];
console.log(fruits.reverse());

Output:

• sort() – The sort() method is used to sort an array alphabetically. This function sorts the values as string by default.

Example:

let fruits = ['mango','apple','grapes'];
console.log(fruits.sort());

Output:

• slice() – The slice() method is used to slice out a piece of an array into a new array. It creates a new array without removing any elements from the source array. It will return the value that has been sliced out from the array.

Example:

let colors = ['red','blue','green','yellow','orange'];
console.log(colors.slice(1,3));

Output:

These were some of the most commonly used JavaScript array methods. With this, we have come to the end of our article. I hope you understood how array methods are used in JavaScript.

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