Unlike HTML, JavaScript is not a markup language, it is a standardized programing language. However, similarly to HTML and CSS, JavaScript is one of the foundation technologies used in creating a website. JavaScript works with text, arrays, dates, and regular expressions. Yet, while using JavaScript you must rely on the host of the website for networking, storage, or graphic conveniences.

Surprisingly, JavaScript originated from C and not Java. Despite having a similar name, JavaScript and Java are unrelated and they both have very different semantics.


(image via http://www.w3schools.com/js/default.asp)
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Another use for JavaScript is not a web-based entity. For example, PDF documents or desktop widgets. It is also used in mobile application and game developments.

The source of information used in this site was derived from wikipedia.org