Privacy. Debian Pastezone. The Django Book. Mozilla Developer Network. JavaScript is a programming language that allows you to implement complex things on web pages.
Every time a web page does more than just sit there and display static information for you to look at — displaying timely content updates, or interactive maps, or animated 2D/3D graphics, or scrolling video jukeboxes, and so on — you can bet that JavaScript is probably involved. Learning pathway JavaScript is arguably more difficult to learn than related technologies such as HTML and CSS.