Introduction to JS in the Browser

JavaScript (JS)

is a lightweight interpreted or JIT-compiled programming language with first-class functions. While it is most well-known as the scripting language for Web pages, many non-browser environments also use it, such as node.js, Apache CouchDB and Adobe Acrobat. JavaScript is a prototype-based, multi-paradigm, dynamic language, supporting object-oriented, imperative, and declarative (e.g. functional programming) styles. Read more about JavaScript.

 

Generate Alert Box if user tries to change text in text input field

<FORM> <INPUT TYPE="text" VALUE= "dont change" NAME = "leavebutton" onChange= "alert('Please dont change this')"> </FORM>