In the JavaScript world Scriptlets are short pieces of code which can be executed through the browser directly. They act on the page in the same wasy as if the user had clicked a button in an application.

An example of a simple Scriptlet is javascript: alert(location.href); void(0);

The best way to add a Scriptlet varies depending on which browser you have:

For Firefox – right click in the Bookmark bar and select New Bookmark