What is JavaScript? Why to Use it?


JavaScript was originally known as LiveScript when it appeared in Netscape 2.0 in 1995, but due to the buzz surrounding Java, Netscape changed its name to JavaScript. Netscape, Internet Explorer, and other web browsers have all incorporated the language’s general-purpose core.

To facilitate JS development, a galore of JavaScript frameworks, libraries, and other tools are available. Nonetheless, sometimes developers like to use plain JavaScript code. Vanilla JS refers to the practice of using JS without any additional tools such as libraries and frameworks.

What is JavaScript?

JS is a scripting language that allows you to create dynamic computer programs. Usually, a JS script is a small script that allows the client-side to interact with the user and create dynamic pages. It’s an object-oriented, interpreted programming language.

JavaScript is used whenever a web page does more than just sit there and display static stuff for you to look at — for example, when it displays timely content updates, interactive maps, dynamic 2D/3D visuals, scrolling video jukeboxes, and so on.

It’s the third of three layers of common web technologies, the first two of which are HTML and CSS. On the client-side, over 97% of websites employ JS for web page behavior, with third-party libraries frequently incorporated. To run the code on the users’ devices, all major web browsers have a dedicated JavaScript engine.

How to Use JavaScript in HTML Code?

There are three ways one can embed JavaScript code in HTML code, and those ways are described below:

1. Inline JavaScript: In this, one has to simply put the JS code within the HTML tag. For example:

<button onclick=" alert('You just clicked a submit button')">Submit</button>

2. Internal JavaScript: Internal JavaScript can be achieved by putting all of the JS code inside the script tag in the HTML body. For example:

Inline JavaScript

3. External Javascript:  You might wish to keep your JavaScript code separate. This is possible using external JavaScript. Here’s how it’s done for such scenarios:

<!-- index.html —>

<script src="./externalfile.js"></script>

<!-- externalfile.js – >

alert(“This is javascript external code”)

The script tag’s src element lets you specify a source for the JavaScript code. This is significant because it instructs the browser to fetch the contents of externalfile.js as well.

Applications of JavaScript

  1. Single Page Applications (SPAs): These are the most widely used JavaScript applications nowadays. These are far more responsive and look like desktop programs. For example, Facebook and Gmail are single-page applications.
  2. Multi-page Applications: These programs operate in a “conventional” manner. Every update in the web application triggers a new page request from the server. They’re bigger than SPAs and take longer than they should. We must transport a large amount of data between the server and the browser, which slows down the program.
  3. Isomorphic Applications: With the advent of NodeJS, JavaScript applications became “isomorphic,” meaning they may run on both the client and the server. These programs come in handy when you need to interact with online sites quickly.

Advantages of JavaScript

Some merits of JavaScript that convince a web developer to use this particular programming language are:

  • As it is an interpreted language and also a client-side scripting language, it takes less time to compile a program as compared to other languages.
  • JS is simple and pretty straightforward for both consumers and developers. It’s also simple to implement, saving web developers a lot of money on dynamic content development.
  • Being an interoperable language, JavaScript works smoothly with different programming languages, so developers use it to create a variety of applications.
  • Since JS is a client-side language, data validation can be done in the browser rather than on the server. The entire webpage does not have to be reloaded if there is a discrepancy. Therefore, only a portion of the page is updated by the browser.
  • Developers can use JavaScript to create appealing web pages using a variety of interfaces. Websites with drag-and-drop components or sliders can have a richer interface. As a result, the user experience on the website enhances.

Disadvantages of Using JS

Now that we’ve gone over the benefits of utilizing JavaScript, let’s have a look at some of its drawbacks:

  • JS can sometimes be used in the wrong way as it is a client-side language, so misusing this language is very easy. Using source code without authentication is one of these activities. Furthermore, it is relatively simple to inject code into the site that undermines the security of data transmitted over the internet.
  • Although some HTML editors have debugging capabilities, they are not as effective as other editors such as C/C++ editors. Furthermore, because the browser displays no errors, the developer can’t notice the issue.
  • Only single inheritance is supported by JavaScript, not multiple inheritance. This object-oriented language feature may be required by some programs.

Why Use JavaScript?

JavaScript is a must-have skill for those who want to become exceptional software engineers, especially if they are in the web development field or want to build a career in the same. Below mentioned points give an idea of why one should use JS:

  • Even when users are offline, JS code functions on their machines.
  • It is a simple language to use. Simply paste your code into an HTML document and specify that it is JavaScript.
  • JS provides the ability to load content into a document as needed by the user without having to reload the entire page. That ability is termed Ajax.
  • Without having to wait for the server to respond and show another page, JS enables you to design highly responsive interfaces that improve the user experience and give dynamic functionality.
  • Principles of unobtrusive JavaScript, sometimes known as defensive programming, allow the programming language to examine what is possible in your browser and react accordingly.
  • JS can assist with the resolution of browser issues or the filling of gaps in browser support, such as CSS layout issues in some browsers.

That’s a lot for a language that was once mocked by programmers who preferred “higher programming languages.”

One reason for JavaScript’s resurgence is that we’re constructing more complex online apps these days, and high interactivity necessitates either Flash (or other plugins) or scripting.

Because JS is a web standard, it is supported natively across browsers and, consequently, it is compatible with other open web standards as well.


Here, we discussed what JavaScript is, its applications, merits, demerits, and reasons to use it. This information will assist a developer in determining when and where to employ JS code for maximum efficiency.

Learning JS for developers is worthwhile as this language can be a great advantage in the modern form of web development.

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