The image has a div covering part of it. If you click on the div, the image does not receive the click event.

The image, the div and the document are listening for click events. Note that even if the DIV is not listening for the event it still blocks it.

If you click on the DIV you should get three alerts with the texts "div", "img" and "document".

This DIV is partially on top of the image, but it shouldn't be blocking the image's clicks