[scriptable, uuid(423fdd3d-41c9-4149-8fe5-b14a1d3912a0)]
interface nsIJSXMLHttpRequest : nsISupports


 Meant to be a script-only mechanism for setting an upload progress event
 This attribute should not be used from native code!!
 This event listener may be called multiple times during the upload..

 After the initial response, all event listeners will be cleared.
 // XXXbz what does that mean, exactly?

 This event listener must be set BEFORE calling open().

 Mozilla only.
attribute nsIDOMEventListener onuploadprogress