Are you using HTTP or FTP upload? If HTTP, are you sure you have "Connection","Close" HTTP header enabled in the server-side script? If not it could explain why cancel does not work as expected. I am using HTTP, yes. I'm not sure what you mean by "Connection","Close" headers, though. I'm pretty new...

I'm using JFileUpload for an asset management system and I want to use the onbeforeunload event to make sure everything is squared away as it should be if they exit the window as the uploader is working. The event cancels the upload and calls another script to handle the files already on the server....