问题
What I am trying to do is to change an image on my webpage when the user mouses over a thumbnail of it. It is easy for me to do it this was because the thumbnail src only has 'tn_' appended to the filename and is otherwise identical.
The problem I'm having is that when I switch the src on the image the attr function returns the img dom element almost instantly while the image itself does not change until the new image loads. I want to have some sort of a callback, so that I can either change the cursor to show a loading symbol, or write loading somewhere on the page while the new image is loading.
How can I do this?
回答1:
You can give the image a load() callback.
$('#imageID').load(function() { .... });
来源：https://stackoverflow.com/questions/4036865/jquery-callback-on-img-src-replacement