JavaScript is an interpreted and lightweight programming language which has wider applications in the web-based developments. The original purpose of the language was to make web pages (HTML) "come alive" by adding dynamic behaviours and interactivity. JavaScript executes in the browser (front-end) and as of today, many backends are also built using JavaScript.

JavaScript is easy to learn, implement and test as it does not require any special software for its execution. All browsers such as Chrome, Safari, Mozilla Firefox on all devices support the interpretation and execution of JavaScript. 

Within web applications, JavaScript may be used for: 

• direct manipulation of HTML elements - adding, removing, showing and hiding of elements at run time. JavaScript may also be used to dynamically style (add CSS) HTML elements.
• validation of form inputs - checking the validity of information entered by a user before processing. This is normally done in cases of user authentication, correction of form inputs before saving to databases, etc.
• notifications - JavaScript may be used to elevate dynamic pop-ups on the screen of webpages in order to show various kind of notifications to users.