What is JavaScript?


The JavaScript programming language is text-based and can be used on both client and server-side. It controls multimedia within web pages and allows them to become interactive. JavaScript empowers a developer to do many things like adding animation to images or updating content automatically on a page. 

JavaScript is what allows you to interact with the vast majority of web pages that you visit. Whether it’s filling out forms, scrolling through maps, or registering for an event, it’s most likely that JavaScript programming is what’s allowing you to do it. 

For example, if you’re on a web page that has a JavaScript-powered shopping cart, you’ll notice that it immediately shows the total cost of what you want to buy including taxes, shipping, etc. Javascript is then used when determining whether the credit card details you entered were valid before transferring those details across the net to the bank for processing. 

What is JavaScript used for?

JavaScript is among the world’s most used programming languages. Without it, we’d be looking at pages that do nothing other than display images and text. HTML may be the bones of a web page, and CSS adds style, but JavaScript programming is what gives it life.

Without this amazing language, businesses would be at a loss. Companies depend on the JavaScript language to interact with their customers in today’s online world. Common uses of Javascript include:

  1. Creating interactive web pages
    As discussed above, JavaScript is responsible for almost any interactions you have with a website that result in a change on the page. Without it, the web would be incredibly limited. Common interactive actions enabled by JavaScript are:
    * Adding items to a basket and making purchases online
    * Expanding or collapsing content blocks at the click of a mouse
    * Playing video or audio files on site
    * Displaying animations
    * Using drop-down menus
  2. Front end development
    There are a number of popular front-end JavaScript frameworks that help websites build great applications for their users. These frameworks include Angular, React and Vue. Some famous applications built using JavaScript are Netflix, PayPal, YouTube and Facebook.
  3. Back end development
    Although JavaScript made a name for itself as a front-end language, being applied to HTML and CSS, it also has impressive qualities as a back-end development language. Frameworks such as Node.js mean that JavaScript can be used to build server-side code. 
  4. Gaming
    JavaScript programming isn’t just useful to standard websites. JavaScript is also responsible for most in-browser games, great for killing a bit of time or for honing your skills if you are just starting off in development. 
  5. Artificial intelligence
    A relatively recent development in the use of JavasScript is in AI. Javascript libraries such as TensorFlow have allowed developers to use JavaScript for machine learning, creating models that can predict future events based on the categorisation of past data. 

The many and varied uses of JavaScript mean that being able to code in it is an in-demand skill around the world. For example, a simple search on Indeed in the UK shows 13,500 vacant roles at the time of writing, so it’s a useful thing to learn if you are thinking of a career in web development. 

Why is JavaScript so Popular?

JavaScript has been around for almost three decades now and its versatile nature, being able to service front-end and back-end development, has made it a mainstay in most developers’ toolboxes. 69.8% of people sayJavaScript is their preferred language to code in. Some of the reasons the language is so popular are:

  • JavaScript is one of the very few programming languages that can be used in all popular browsers.
  • JavaScript can be used to build apps on mobile as well as on the web. This meant it was perfectly positioned to dominate when smartphones took off.
  • Because JavaScript is so popular there are a lot of ready-to-go frameworks and libraries that can kick off projects, saving a lot of cost, time and effort for development teams.

How to use JavaScript

Web browsers are built to understand HTML and CSS and convert those languages into a visual display on the screen. To do this, the browser uses what’s called a layout or rendering engine. This is the part of the web browser that understands HTML and CSS.

A browser also contains what’s called a JavaScript interpreter. This is the part of the browser that understands JavaScript and can execute the steps of a JavaScript program.

A web browser is usually expecting HTML. But we must specifically tell the browser when JavaScript is included. To do this, we use the <script> tag. This is similar to the <style> tag used in CSS. Also, like CSS, JavaScript can be included in the head element or accessed from an external file. JavaScript doesn’t have to be confined to the head element, though. You can also insert script elements in the body area, creating islands of behaviour or functionality throughout the page.  

Developers often recommend that you place your JavaScript as the last element inside the body of a page. This is because javascript mainly operates on HTML elements as part of a task.  

JavaScript is designed to be able to travel the element family tree or DOM and access, modify, add or even delete elements. If the JavaScript appears in the head of a page, it might attempt to access elements that the browser has not yet interpreted. That is, they might not yet have been added to the family tree in memory. These elements need to have first been read by the browser interpreter for JavaScript to access them on the tree.

5 Day Coding Challenge – learn JavaScript basics

Code Institute’s free 5 Day Coding Challenge can offer you some insights into HTML, CSS & JavaScript. The best thing about the challenge, other than learning the basics, is that it’ll let you know if you have an aptitude for software development. Register for this weekly challenge through the form below. Alternatively, if you want to learn more about our Full Stack Software Development programme, follow this link

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