Top must-know Features of JavaScript

In this tutorial, we will understand the special features of Javascript.

Javascript is a popular programming language. Javascript features are flexible. Many open-source libraries are available. GitHub contains a large volume of Javascript code by developers across the world. Javascript works well in the front end and back end.

Javascript has a simple syntax. Without any settings, anyone can execute Javascript programs and make them user-friendly. One individual having basic knowledge of HTML, CSS and coding can work with Javascript.

Features of Javascript


Javascript executes the client-side script in the browser.


The browser interprets JavaScript code.

Event Handling

Events are actions. Javascript provides event-handling options.

Light Weight

As Javascript is not a compiled language, source code never changes to byte code before running time. Low-end devices can also run Javascript because of its lightweight feature.

Case Sensitive

In Javascript, names, variables, keywords, and functions are case-sensitive.

Control Statements

Javascript has control statements like if-else-if, switch case, and loop. Users can write complex code using these control statements.

Objects as first-class Citizens

Javascript arrays, functions, and symbols are objects which can inherit the Object prototype properties. Objects being first-class citizens means Objects can do all tasks.

Supports Functional Programming

Javascript functions can be an argument to another function, can call by reference, and can assign to a variable.

Dynamic Typing

Javascript variables can have any value type. The same variable can have a string value, an integer value, or any other.

Client-side Validations

Javascript client-side validations allow users to submit valid data to the server during a form submission.

Platform Independent

Javascript will run in the same way in all systems with any operating system.

Async Processing

Javascript async-await and promise features provide asynchronous nature. As the processes run in parallel, it improves processing time and responsiveness.


Javascript follows 'Object.prototype' functions instead of class inheritance.

Nullish Coalescing Operator (??)

The nullish coalescing operator returns the right side operand if the left side operand is null. If the left operand is not 'null', the operator returns the left side operand value. This operator helps to avoid Boolean operator errors.

Logical nullish assignment (??=)

It is the shorthand of


Styling Console Log

Javascript consoles can have styles. For example, see the block below.

console.log('%cText %cValue', 'color:black; cursor:pointer', 'color: green;');

The first set of styles applies to the first string with %c, and the second %c gets the second style set for the second string.

Object Shorthand

Object shorthand can save space and time by allowing users to use the same name for assigning variables and key values.

const name='Egan', id=1; //The above snippet can be as follows const egan={ name, id } console.log(egan); //Output {name:'Egan', id:1}

Optional chaining (?.)

Javascript optional chaining optimizes the general null check in the example below.

var obj={ data:{ id: 1; } } //General null check if( && //Optional chaining

Defer/Async Loading

Javascript 'defer' and async download file during HTML parsing and optimizes page load time. Async scripts run immediately after the download. Defer scripts execute only in the Dom order.

Simple client-side Calculations

Javascript can execute simple client-side calculations on the browser.

Large Browser Control

Javascript gives priority to the browser over the server.

Date and Time Handling

Javascript has built-in functions for getting 'date' and time.

HTML Content Generation

Javascript allows users to add dynamic HTML content upon doing some action on the page.

The Browser And OS Detection

Javascript has built-in code to detect the browser that the user uses.

Let & Const Keywords

Javascript replaces the var keyword with the let and const keywords and has a block-level scope.

Arrow Functions

Javascript helps to optimize syntax in anonymous functions with the arrow function syntax.

Template Literal

Javascript permits saving a variable as a string and saves development time.

New Array Functions

Javascript array functions enable code optimization. The regular array has an integer index, and the associative array has string index.

Default Parameters

Javascript avoids error scenarios with undefined values using the default parameters.

Property Shorthand

Javascript has several shorthand methods like .get() that saves coding time and cost.

Similar Syntax of Java

Javascript syntax and Java syntax are more similar, and it helps developers to work in both programming languages.

If else Statement

Javascript 'if else' conditional statements perform logical operations.

Looping Statements

Javascript loops allow developers to run the same code multiple times using a loop.


Javascript allows large integer values. Javascript engines support BigInt differently.

Dynamic Import

The Javascript dynamic import function allows adding any files at run time.


Javascript Promise.allSettled method accepts the promise array only after resolving or rejecting all the promises.

String matchAll

Javascript string.matchAll() returns all the match groups in a regular expression.


Javascript globalThis points to the global object without considering the window object or self-object.

Module Namespace Exports

Javascript Module Namespace import export syntax is as follows.

import * as utils from'./utils.mjs';
export {utils}

Well Defined for-in Order

Javascript 'for(a in b)' had no execution order till 2020. ES2020 gave the specification.


Javascript import.meta gives the meta information of a script tag.

<script type='module' src='module.js'>
{url: 'file':'//home/user/module.js'}

Negative Indexing with .at()

Javascript array indexing with array length minus procedure is an old method. The function .at() can replace this task.

let arr=[10, 20, 30];;//Prints 20


Javascript hasOwn property is an extension of hasOwnProperty. Javascript hasOwn is a static method.

let obj = Object.create(null);
Object.hasOwnProperty(obj, 'hasOwnProperty');

//Cannot convert the object to the primitive value
Object.hasOwn(obj, 'hasOwnProperty'); //true

Class Static Block

Javascript classes can have static items.

class Color {
   static blue;
   static { = 'blueberry';

Error Cause

Javascript Error class provides an error cause report as well.

throw new Error('Error message', { cause: rootCause });


Javascript has unique features as well as the features of Object-oriented programming and Java language. All the features discussed and the remaining features make Javascript a powerful programming language.

Updated on: 28-Dec-2022

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