How to simulate magnifying glass on Web-page image (Javascript)?

Question

Google has the coolest effects - once it was a Pac-man game, today is apparently the 160th anniversary of the first World Fair, and Google\'s logo has an image of i

Answer 1

Looks like they're using two images, one for the logo and one for the zoom (the zoomed one is actually sliced, to run the animations separately...?) They probably detect if the mouse is over the normal logo, then show the yellow circle and attach it to the mouse position. Then showing the other image, shifting it opposite of the mouse. Or something similar.