Introduction to JavaScript JavaScript is one of the most popular programming languages on the Internet, used to add interactivity to web pages, process data, and create various applications (mobile applications, desktop applications, games, etc.). This language can be used in HTML and web, and can be widely used in servers, PCs, laptops, tablets, smartphones and other devices. JavaScript is a scripting language JavaScript is a lightweight programming language. JavaScript is programming code that can be inserted into HTML pages. When JavaScript is inserted into an HTML page, it can be executed by all modern browsers. JavaScript is easy to learn.