view window jquery conditional

I am working on a menu bar that is fully responsive, and I would like for the images that are the menu options to switch to bigger (premade) larger versions of the same images after the window gets wider than 1200px. The objective is to help there not be as much blank space on bigger viewing windows. I was thinking the best way to do it would be to have some sort of jQuery conditional statement, but if there is an easier way to do that, I would be open to suggestions

Please be very detailed, I am not a pro yet.