Deprecated since Gecko 17 (Firefox 17 / Thunderbird 17 / SeaMonkey 2.14)
This feature has been removed from the Web. Though some browsers may still support it, it is in the process of being dropped. Do not use it in old or new projects. Pages or Web apps using it may break at any time.
||A mechanism for setting an upload progress event listener. This event listener may be called multiple times during the upload.|
You must call
open() on the
XMLHttpRequest before setting any event listeners on it.