What is JavaScript?

Coding for Beginners
Written by:
Courtney Grace
Published on:
July 1, 2021

Dive into a comprehensive guide that explores JavaScript, providing a detailed understanding of what it is and how it functions. Perfect for beginners and experts alike, this resource offers in-depth knowledge about JS.

Software engineers use a whole slew of languages to build web applications, mobile applications, and websites. JavaScript is one of those languages. It’s been around for years.

Let’s dive into all things JavaScript:

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What is JavaScript and why is it used?

JavaScript is aptly named as it’s a scripting language. PHP and Python are other examples of scripting languages.

As Career Karma explains, scripting languages use a program known as an interpreter to translate commands. They don’t require a compilation step, and they do not have source code because there’s only one type of code.

JavaScript frameworks are primarily used to make web pages more dynamic and interactive. Oftentimes, developers will utilize web frameworks like React, View, or Angular to build complex web apps like Google Docs. These are JavaScript libraries, too! They all make it easier for developers to add, remove, and alter elements on a web page so they can develop new features faster. In short, JavaScript coders create features for web pages and mobile apps. The user interface is top priority for a web developer or engineer.

There are three major “types” of JavaScript

  1. Client-side JS is an extended version of JavaScript that enables the front-end enhancement and manipulation of web pages, web servers, and client browsers
  2. Server-side JS is an extended version of JavaScript that enables back-end access to databases, file systems, and servers
  3. Core JavaScript is the base JavaScript language. Both client-side and server-side JavaScript are dependent on the core

If you’ve been on any web browser — including Google Chrome, Firefox, and Safari — you’ve likely had to enable JavaScript at one point for certain functionalities of a webpage to work. Nowadays, it’s typically done for you, and the user has to go in and manually turn it off.

What’s the difference between JavaScript and Java?

Despite the similarity in name, JavaScript and Java are not the same. Engineers typically learn both and use them for different tasks, but we teach node.js at App Academy which lets JavaScript run on a server, much like many Java applications do. In that respect, they are interchangeable.

When and how was JavaScript created?

Longtime web developers and other coding professionals have known JavaScript for decades now. It has a storied history — one that explains the JavaScript and Java likeness — that started in the early days of the Internet.

According to auth0, pioneering web company Netscape licensed the original Java language, but many within the organization determined a “lighter” scripting language also needed for Netscape’s Navigator browser to appeal to a larger breadth of programmers. Netscape contracted Brendan Eich (coined the “father of JavaScript” to create such a language that would make a then-static web significantly more dynamic.

Eich was under a significant amount of pressure as competitors were in the process of making their own version of a programing language tat appealed to designers, animators, and creators. Within a few weeks, JavaScript — at the time, known as Mocha — was prototyped and working. Designed initially to complement Java, the features that were baked into this initial language reached far beyond its initial intention.

Many of those features are cornerstones of the JavaScript we know today, though new iterations are constantly being released. In fact, the 2021 spec was just recently approved and the 2022 spec is currently getting drafted.

What can you do with JavaScript?

JavaScript is sort of the icing on the cake for programmers. In some cases, you write JavaScript code to implement dynamic elements that make things move, jump, or scroll. Very few web pages, if any, don’t incorporate these elements in some way, so it’s definitely a must-know skill (or, at the very least, something like JavaScript is) for all engineers.

JavaScript is also a programming language in its own right. It does a lot of the things other languages like, say, Python can. Make Use Of lists these as:

  • Store and retrieve data values
  • Declare variables
  • Define objects and classes
  • Load and use external modules
  • Write event handlers that respond to click events
  • Write server code
  • Define and invoke functions

Unfortunately, JavaScript — as many other languages are — is subject to use by hackers and ransomware creators. In many cases, it’s used for computer exploits. An exploit takes advantage of a weakness in an operating system, application or any other software code (BullGuard).

JavaScript is also used in close tandem with HML & CSS, though JS is a scripting language and HTML & CSS are markup languages.

At a high level, HTML provides the basic structure of a website, which is enhanced and modified by other technologies like CSS andJavaScript. CSS controls the presentation, formatting, and layout of that webpage. JavaScript is the icing on the cake; any interactive elements, scrolling, clicking, or movement is created using it.

How does JavaScript work?

JavaScript is “Just in Time Compiled”. That means, when JavaScript code runs on a computer, it’s actually being run through a fancy program called a runtime (or an engine). One of the most popular JavaScript engines is the open-source V8 engine (it belongs to Google and Google Chrome. Microsoft has an engine called Chakra.

This engine is an incredibly complex piece of software, but you don’t need to know how it works or install it to get started with JavaScript, Instead, you have a JavaScript engine inside the very web browser you’re using to view this page! All it takes is a text file with the extension .js and you can get started writing and running.

Examples of JavaScript on the web

Nearly every major website uses JavaScript to some degree. This includes Google, YouTube, Amazon, LinkedIn, eBay, Twitter, and Facebook, among others.

Because of how dynamic and interactive JS is, there are endless cool examples of it online. Engaging elements make a web page or a mobile application more interesting and memorable.

Filippo Bello.

Fillippo Bello

Italian-based design agency Adoratorio brought 3-D artist Filippo Bello’s brand to life by creating depth and transition and zoom effects that paid homage to the artists’ medium.


residente - what is javascript example - app academy

Residente is a musical artist who uses his webpage for interactivity around his projects and travels. Users can scroll around the map to read stories and see photos and videos from everywhere he’s been.



Created to celebrate French cycling culture (Tour de France included), this graphic design project feels seamless as you scroll through different variations of bicycles, sceneries, and color schemes. It was built using JavaScript to create whimsical interaction for the user.

Why You Should Learn JavaScript

According to Payscale, the average salary for JavaScript developers is $83,311 per year or $29.82 per hour. Indeed calculated the salary standing at $110,673 a year or $47.49 per hour. However, the average salary according to Salary Expert is $99,761 per year.

However, at App Academy, we don’t just help students become single-language developers. We teach a world-class, end-to-end software engineering curriculum that gets people jobs.

JavaScript is a part of our curriculum because it really is that popular. In fact, many companies use it for on-the-spot coding challenges during interviews. It’s beginner-friendly because of that smaller error margin and a bustling online community (think Reddit and Stack Overflow) to lean on for advice while you’re learning. Plus, you don’t need a development environment since JavaScript comes baked into every web browser.

Even better: JavaScript expertise is in-demand — and not just for software engineers. Anyone in marketing, business and data administration, entrepreneurship, or who works on the web in any capacity could benefit from having working JavaScript knowledge on their resume. As tech continues to grow increasingly omnipresent, it won’t be long before JS is a requirement for other types of professionals, too.

Ways to Learn JavaScript

Like any programming language, JavaScript requires practice and an understanding of key principles. Luckily, anyone with a text editor installed on their computer (or the default ones that come with your particular machine) can start writing JavaScript code that can be executed on a web browser. That’s not what software engineers do on the job, but it works for those who are trying to teach themselves the language or simply want to try their hand at writing a few lines of code.

In order to broaden that knowledge, a bootcamp is the sure-fire way to land you a job as an engineer, with JavaScript (and other important languages) under your belt. For San Francisco Bay Area and New York residents, our in-person campus-based programs build solid programmers in just 16 weeks. For everyone else around the country (and the world, if they can make lecture times!), we offer an Online Immersive Coding Bootcamp; if you don’t get a concept, you can re-do that portion of the curriculum without penalty!

There are also countless free and affordable courses available for learning JavaScript One of those happens to be our own free program, App Academy Open. It doesn’t cost you anything, and you can learn important other skills and languages in addition to JavaScript, if you so choose.

Sign up entirely for free here: https://www.appacademy.io/course/app-academy-open.


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