Inline JavaScript
Inline JavaScript - e.g. the use of HTML attributes such as: onclick, onmouseover, onmouseout, etc - is an outright no-no. Do NOT do this. Instead, opt for event binding.
jQuery
The Brotherhood standardizes on the jQuery library. All JavaScript should be written using jQuery; either using Core jQuery, jQuery plugins, or DJB created jQuery plugins.
Script Inclusion
Including JavaScript within script tags in the HTML is not advised. Use an external file where possible. This allows the individual files to be cached by browsers independent of the HTML file.