What is JavaScript? Why design websites with JavaScript

JavaScript (JS) is a popular programming language behind many web features and applications, from basic to complex. Although there are many modern languages today, JavaScript remains a solid foundation and an essential language for any developer to know. To understand what JavaScript is and why this web development language matters, read on MONA Media through the article below.

What is JavaScript?

JavaScript is a programming language released by Brendan Eich in 1995. It turns websites from static to dynamic, adds interactivity to ease server load, and improves the user experience.

Many people assume JavaScript was built on Java. It was not. The name was a play on Java, chosen to draw attention to the new language on the back of Java's popularity at the time.

Today JavaScript runs well beyond the browser (client-side). It is a cross-platform language that runs in many server environments, desktop software and mobile apps.

How JavaScript works

Developers usually create a file and either embed it directly in the HTML file or call it from the website's HTML.

When you visit a site, the browser automatically finds the JavaScript file that is called, or the code embedded directly in the site's HTML. That code runs right in the user's browser. This is why JavaScript is also called a client-side language rather than a server-side one.

Websites built with JavaScript

A website usually has 3 basic parts: HTML, CSS and JavaScript. HTML defines content and structure, while CSS defines colors, shapes, fonts and so on. Changes made in HTML and CSS are mostly static. They cannot produce eye-catching motion such as rotating images, click effects, validating entered information or showing messages to users.

JavaScript, the third part, turns all of these actions from static to dynamic. The 3 parts together make a complete website with a quality interface (UI) and user experience (UX).

As technology keeps advancing, HTML and CSS have improved a lot. Instead of JavaScript, web designers can use HTML and CSS for lively effects. But with JavaScript, the same work is faster and takes far less effort. That is why JavaScript is still so popular today.

Advantages of designing websites with JavaScript

So what makes it the backbone of a modern website, and the most widely used web development language in the world more than 20 years after its release?

For website owners and designers

Saves server bandwidth because JavaScript runs on the user's machine

JS used in website design saves a lot of server bandwidth because it runs directly on the user's device. This was also the original goal of its creator, Brendan Eich. In the past, servers were huge, took up a lot of space and cost businesses a great deal.

That is why scripts today run in the user's browser, which improves performance, extends server life and saves bandwidth.

Flexible to run, widely compatible

To run it, the browser only needs to download the JavaScript file from a separate domain or read it embedded in the site's HTML. Nothing else needs to be downloaded. So JS runs on nearly all popular browsers today, such as Cốc Cốc, Chrome, Firefox, Microsoft, Safari and more.

Also, most web browsers have a built-in JavaScript interpreter, so users can use it right away without downloading anything extra, which cuts the chance of JavaScript functions failing to run. This is very handy when there is no internet connection.

JavaScript works on every popular web browser

Easy to test and troubleshoot

With so many browsers supporting it, testing and fixing problems is easier. Most browsers today have built-in JavaScript error tools in the browser console. Debuggers also include a breakpoint feature, which marks a spot so you can check that it runs correctly and track it while it works.

JavaScript has a readable structure with clear rules, so finding, debugging and fixing problems is much simpler.

Creates eye-catching effects and useful features for users

One standout advantage that people like about JavaScript is its ability to create lively, engaging effects and handy features. It turns plain, simple, rigid images into something vivid and engaging.

Extensible and highly customizable to meet needs website design as well as what users need when they need it. Beyond its strong features and improvements, in the hands of experienced developers JavaScript shows its full power for sophisticated, complex functions, especially when building large web apps with many features.

For users

Websites that use this programming language give users a better experience. When you browse, you are quickly drawn in by useful features, engaging animations, smooth scrolling, and fast, responsive interaction. These make users feel comfortable, enjoy the site and trust it more.

Disadvantages of designing websites with JavaScript

Like any programming language, it comes with some drawbacks.

For website owners and designers:

JavaScript features may not run

Some browsers do not support JavaScript or have it turned off, so its features may not work. In that case, you can handle it in a few ways:

• Replace JavaScript with HTML and CSS for some parts of the website (where possible)
• Test the website with JavaScript off, and show a message asking users to turn JavaScript on for a better experience.
• Tell users that the website needs JavaScript for certain features.

JavaScript behaves differently depending on the browser and the user's device

JavaScript is known for the line "write once, run anywhere", but in practice it does not run the same way in every browser. It depends on each device's and browser's performance and settings. So you may sometimes see feature errors or inconsistent display.

So test the website on a range of browsers and platforms to catch and fix problems in time.

For users

Impact on device performance

JavaScript was designed to reduce server load, which means the load shifts to the user's device. When there is too much to process or the JavaScript effects are too heavy, the user's device performance can suffer. So website design need to optimize their code and use lightweight JavaScript libraries to reduce the load on the user's device.

Vulnerable to data theft and malicious code injection

With more than 90% of websites using JavaScript, it has become an attractive target for hackers. JavaScript itself also still has quite a few security holes. This creates a serious risk to data protection and of malicious code injection.

More dangerous still, malicious code runs on the user's own device or browser. If attacked, hackers can easily steal information or take control of the user's device for harmful purposes.

So JavaScript web designers need to strengthen security, monitor regularly, and test and maintain security patching. This is also something Mona's website designers take seriously and do carefully, to keep users' browsers fully safe.

Key uses of JavaScript in website design

With constant improvement and upgrades, JavaScript can now do more sophisticated and complex things, making interaction and user experience more engaging. Here are some key uses of the JavaScript programming language

Fixing layout problems, improving appearance

JavaScript can detect the user's device and details such as the browser, screen resolution and so on. This information helps improve how the site looks and adjust the layout sensibly, which supports responsive design.

In addition, some display features built with CSS3 may not be supported by a browser. This kind of problem can be fixed by using JavaScript instead.

Responsive design changes a web page's size and layout to fit the screen size

Creating lively, eye-catching effects

For a modern website, motion effects are essential. Effects on each post or page, transitions between menus, even switching between pictures in an album all need engaging effects to keep the site attractive.

These effects and animations breathe new life into a static website and bring fresh, more enjoyable interaction. For example, with Tet (Vietnamese Lunar New Year) coming up, you may want to design a Tet website with effects and colors suited to the holiday, to set the mood and improve the visitor's experience.

You can build these effects with CSS3, but JavaScript can make them smoother and give a livelier, more intuitive experience.

Improving interaction with users

Besides changing effects, there are many other appealing features, such as:

Shopping cart

A shopping cart is for online stores. With it, you don't have to write product lists by hand on paper. Lists get especially messy when items come with different discounts and offers. A shopping cart handles all of it. You quickly see how much you will pay and the full order details before checkout.

User name checking

When you type in the user name you want, JavaScript can instantly check the database to see whether it is already taken. This is fully automatic and immediate: no page reload, no database call, things HTML and CSS cannot do.

Search keyword suggestions

With keyword suggestions, Google automatically works out what you are looking for and shows a list of the most relevant suggestions.

Live updates

With no reload needed, a page can update itself with the latest information and features for the tool or site.

Video playback

To play video on the web, the browser must have JavaScript, whether the video is stored locally or comes from any other source.

Automation

Apps become more useful and enjoyable when they run automatically. JavaScript can run a scripted series of actions as soon as a user opens a web page.

Triggering JavaScript commands can also depend on other conditions, such as hovering over a certain area, or even the user being inactive for a set period.

This only works with JavaScript, not CSS. A clear example is game websites. You cannot build a game site with HTML and CSS alone, because only JavaScript can handle hovering, mouse clicks and key presses. Game content can also change without reloading the page when you use JavaScript.

Automation lets JavaScript power complex web apps

Summary

Those are concrete examples of JavaScript in website design. From the concept of what JavaScript is and the information Mona has provided, you can see that using JavaScript in web design brings many benefits. It offers solutions that improve interactive features and the user experience.

Design professionals still rely on the power of JavaScript to build modern, high-quality websites. This is especially true today, when most websites are effectively web-based applications. In that role, JavaScript is at the core of popular web apps used every day, such as Gmail, Google Docs and Google Calendar.

If a browser does not support or has turned off JavaScript you cannot use these tools, or even social platforms such as YouTube and Instagram. Without JavaScript, the internet would be far less convenient.