What Is Javascript?

In the world of web design, javascript is what gives life to a webpage. It’s what allows a website to interact with the user and it’s what makes dynamic websites possible. It’s the reason that we can use drop-down menus, form validation, real time data updates and more. Almost all web browsers include a javascript engine and it’s one of the most widely used programming languages in the world.

When you open a page in a browser, it goes through two phases: the memory creation phase and then the code execution phase. During the memory creation phase, javascript scans the page for variables and functions. When it encounters a variable, it assigns that value to that variable in memory (for example, var a = 2 in the code above). Once a variable has been assigned a value, it can be accessed and called upon by any function in that block. Variables are either global, also known as block-scoped or local, or function-scoped depending on their declaration.

It’s this flexibility that fueled javascript’s rise to becoming the most popular browser language. It’s also what allows a website to communicate with backend servers to retrieve and process data.

The front end of many common websites is built entirely with javascript, including Facebook, YouTube and Twitter. It’s used to make web pages more interactive, add animations and give the user a better experience. It’s also what enables web pages to update content without having to reload the entire page. This is how you get those real time updates that are so popular on news and social media sites.

Javascript is also what enables us to use chat widgets, contact forms and video and audio player on a website. It’s the reason you can see live stock or crypto prices on a website or why your online shopping cart automatically calculates total cost before requesting credit card information.

Almost all modern mobile phones also have a javascript engine and it’s the reason that we can use apps on those devices to connect to social networks or get directions. They can even run web applications like Twitter and Instagram, which are also made with javascript.

While HTML provides the bones and CSS adds style, javascript is what brings the whole thing to life. While it can be challenging to learn, it’s a powerful language that’s responsible for many of the most popular websites in the world. It’s important to keep an eye on your javascript performance because it can impact your Core Web Vitals, which Google developed to determine the quality of your website. Tools like Semrush can help identify javascript issues on your pages and ensure that they aren’t slowing down the user experience.