the $F() function will returns the value of form element.
$F(“form_element_id”)
Does it need a description anymore??

The dollar function is one of the Prototype Utility Function. $() is the most frequently used prototype’s function. basically it was used to refer an element in the HTML page. The function is quickly shorthand for getElementById.
The usual function identifying an element is:
document.getElementById(“element_id”)
The $() function reduces the code to:
$(“element_id”)
For example, you can set the CSS [...]

Prototype is the most popular Ajax framework. It used by many giant-website such : Apple, Gucci, etc… The Prototype JavaScript Framework is a JavaScript framework created by Sam Stephenson. Prorotype is implemented as a single file of JavaScript code “prototype.js”.
Prototype is also used as the low layer for many framework, for example: script.aculo.us, Rico, ExtJS, [...]