JavaScript

JavaScript (also known by its acronym JS; hereinafter, JS) is the programming language that serves as the cornerstone for the World Wide Web (WWW). To display any webpage that belongs to WWW, nearly every web browser and every major web browser provides support to three webpage languages. HTML is a markup language that forms the webpage skeleton, CSS is a style-sheet language that allows for graphic consistency throughout a number of pages, and JS makes everything that the first two cannot. That "everything" includes overriding of HTML and/or CSS.

JS conforms to the ECMAScript specification.