在完成所有请求之前，多个AJAX请求不会调用onSuccess

Ok, so I'm working on a little photo gallery that will load a set of images using AJAX. Basically it will load a 'loading.gif' placeholder image, make an AJAX request to generate the thumbnail image. PHP page generates the thumbnail and sends a confirmation that the image has been generated and the path of it. My onSuccess should then replace the loading.gif with the actual thumbnail.Ok, so I'm working on a little photo gallery th