What is JavaScript and what is it used for online?

When you browse the web, the web pages you interact with are presented to you using three technologies: HTML, CSS, and what we’ll discuss in this article: JavaScript.

Of the three, JavaScript is the most advanced. It adds dynamic functionality to web pages, making them much more complex and interactive. Without JavaScript, some of your favorite websites wouldn’t be possible.

In this article, let’s explain what JavaScript is, how it works, and its many uses online.

What is JavaScript?

JavaScript is a scripting language. HTML, one of its most popular relatives, is a markup language. The main difference between the two is that markup languages ​​are structural and prepare the look and design of a page. A markup language is functionally presentable while a scripting language is logical and algorithmic.

In layman’s terms, HTML changes the way web pages look, while JavaScript actually provides computational functionality. In HTML, there isn’t even a way to evaluate a simple equation like 1+1. JavaScript can do that and much more.

JavaScript can be implemented on both the server and client side. Client-side JavaScript is most common, where JavaScript code is referenced via HTML and interpreted by the web browser. This code can do a lot more than just change the look of a page, such as dynamically generating HTML content, prompting user input, and more.

In short, JavaScript is a lightweight, interpreted scripting language that can improve the interactivity of a website.

How is JavaScript used online?

As with almost any scripting language, the possibilities are limited to what you can think of. If you have the skills and can dream it, you should be able to make it.

However, there are some common JavaScript scripts that the web wouldn’t be the same without. Let’s discuss some of the most popular use cases for JavaScript.

Form Validation

If you’ve ever filled out a signup form only to be told your username or password was too short, that was JavaScript in action!

Form validation can be done in a number of different scripting languages, but JavaScript allows it to be done dynamically and without posting data. This can reduce server costs through lower bandwidth, and is a great way to avoid user frustration.

It’s never fun to submit a form and find out afterwards that your details were not valid. JavaScript can do this on the fly.

Converters and Calculators

Be it Fahrenheit to Celsius, USD to EUR or the like, dynamically converting data is something JavaScript excels at. If you’ve ever taken a JavaScript course, one of your first lessons will probably be to create something like a interest calculator† It’s a great learning experience that introduces many of the basics of JavaScript.

Client-side JavaScript is one of the best solutions for handling such calculations.

Random Generators

Math.random() is a favorite function of many JavaScript enthusiasts, and it is extremely useful. It allows to create a random floating point number between 0 and 1, which enables many smart scripts.

One of the most popular scripts of this kind is a random ppassword generator† You can find these all over the web and they are a reliable source for random password generation, as client-side JavaScript doesn’t interact with the server, so it’s never cached or behind the scenes.


That’s right – JavaScript can even be used to code your own games. While client-side JavaScript doesn’t support any kind of online, cooperative experience, single-player games or games that can be played by two users on the same keyboard are quite possible.

Here are a few classic examples:

JavaScript is a seriously good scripting language that works even for not-so-serious projects!

If you’re already well versed in HTML and CSS, JavaScript is a great next step that can really improve your coding game. If coding isn’t your thing, this article should help you appreciate the functionality this scripting language has brought to millions of websites. The internet wouldn’t be the same without JavaScript.

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