JavaScript is a programming language. It was developed by Netscape and is used to add interactivity, graphic enhancement, and automation to websites.

Essentially, there are three elements when designing websites from scratch: HTML, CSS, and JavaScript.

HTML is basically the core of your website, and it is the one that gives it structure. Although it is the most important one, this code is static and doesn’t add much functionality or dynamic elements to the page.

CSS goes a little beyond that and allows you to add style to the HTML code. With CSS, you are able to add color, backgrounds, layouts, and other formatting features. You can add these directly on the HTML code or through a separate file.

JavaScript works with client-based scripting. This means that the code is processed on the client’s side, in this case, your computer browser. HTML, on the other hand, runs on server-side scripting, processing the information on the servers.

JavaScript code can be written directly in the HTML source code, by using the <script> function or tags. Or, it can be linked/referenced as a separate document like in CSS. JavaScript has a great number of libraries and platforms, which include jQuery, AngularJS, ReactJS, EmberJS, and more.

These libraries are pre-written JavaScript code that ease the work for web developers.

How important is JavaScript for SEO?

It boosts crawlability, the ability a search engine has to crawl your website. Any good SEO company knows that these crawlers or bots need to scan your website so they can have an idea of what it contains. However, relying heavily on JavaScript can sometimes affect performance.

For example, search engines are often blocked from crawling JavaScript, making it impossible for them to examine your site. Since they do not see the whole content of your website, they could flag this as cloaking. Cloaking is purposely hiding content from your site or presenting users and search engines with different versions of your site. This can hinder your website’s ranking.