Add onload event and javascript to single joomla page

I have a small job to add an onload event to a single page of a joomla site. There is a body chart, that when moused over related images appear showing the different parts of the body. I have taken it from a previous site that was html and css, and am not sure the best way to add the java script and body onload event that I want only on a single page. My main concern is that this doesn't create conflicts with extensions that are installed and that the event is initiated on the single page it is to work on.