ProgressEvent

void initProgressEvent(
    in DOMString typeArg, 
    in boolean canBubbleArg, 
    in boolean cancelableArg, 
    in boolean lengthComputableArg, 
    in unsigned long loadedArg, 
    in unsigned long totalArg); 

readonly attribute boolean lengthComputable; 

readonly attribute unsigned long loaded; 

readonly attribute unsigned long total;