Where is it that checks for an allowed file extension eg. JPG .GIF and allows that to be uploaded. I want to try something and i can't seem to find the file.
In Chevereto it uses the Upload class (isValidImageExtension, isValidImageMime) to validate $_FILES uploaded. If an extension other than what Chevereto haves by default is not listed, ImageConvert class is used to help to create a readable image that a browser can read. Not only that Chevereto has hard coded javascript for default extensions allowed but you can add on it from the CHV.fn.uploader object otherwise extensions other than the defaults are not selectable to upload.