JavaScript is a general purpose, high level, dynamic, object orientated, interpreted programming language. It also supports imperative and functional programming models. It has a syntax similar to the C, C++, C# and Java derived languages. However there is no relationship between JavaScript and the Java language beyond the similar names. JavaScript differs from the C-based language family in that it is loosely typed. Variables do not need to have a type defined before use. While it is a general purpose programming language, JavaScript has found its main use as a client-side browser based scripting language for web pages and web applications. JavaScript, HTML and CSS provide the three pillars for creating the client facing components of web applications with JavaScript providing the logic to complement HTML and CSS produced pages.

The popularity of JavaScript has exploded over the last decade. One metric that confirms this is that it was the most popular language used for new open source projects on the popular GitHub code sharing site in 2014-2015.