It is a programming language which allows script to be written to enhance the functionality of Web pages. The script is either embedded within the page's HTML code or it can be in a separate file which is called as required. JavaScript programming can be dangerous if not properly implemented and it is not likely that most teachers authoring Web-based courses would become expert programmers. It is easy, however, to take some standard JavaScript and incorporate within your own pages.
Some examples follow.
A Return or Back Button - this takes the user back to the previously viewed page. On Click Alert Please click to go to the Glossary. On Mouseover Alert Boojum.