Javascript IF statement

I am looking for code to employee a certain if statement. This will be in the head section of the html document and I need it to do this:

if (“page link that has been clicked” does not contain “www.ourorg.org” somewhere in the link)

msgbox(“disclaimer, you are leaving our stuff adn going to someone else’s stuff so don’t hold us accountable. Bye”)

end if

The only part that I need help with is that if paragraph. I don’t know what thing I would use to indicate if a link is clickedand I don’t know how to tell it to check the link for a certain string’s partial existance.

Any help?