Indicate that a user has left a page? External HTML Object questions?

Is it is possible to have lectora launch a script from an External HTML Object if the user leaves a page by any means. Basically, is there some sort of event that fires when a user leaves a page, and is it possible to add a function call of some sort to it. We are trying to run a script that writes to a DB when the user enter the page, and when they leave this will allow us to figure out the person's time per page which is a requirement of our course.

Also, is it possible to run a script from an External HTML Object at any point other than when the page loads?