javascript - Attempting to simulate a wheel event [Firefox] -

to clarify example, want simulate scroll event @ center of open window. should affect reasonably main scrolling element on given page.

here relevant pages
https://developer.mozilla.org/en-us/docs/web/api/wheelevent/wheelevent
https://developer.mozilla.org/en-us/docs/web/api/mouseevent/mouseevent#values

and here's i've tried.

scroll_evt = new wheelevent('wheel', {     deltay:    10.0,     deltamode: wheelevent.dom_delta_line,     clientx:   content.innerwidth/2,     clienty:   content.innerheight/2 });  -> wheel { target: null, buttons: 0, clientx: 520, clienty: 320, layerx: 0, layery: 0 } 

however, despite no errors, dispatching event seems not have effect.

window.dispatchevent(scroll_evt); -> true 

so i'm left wonder: there critical property i'm missing in initializer? window appropriate target event? i'm out of ideas.

update

this works.
https://developer.mozilla.org/en-us/docs/mozilla/tech/xpcom/reference/interface/nsidomwindowutils#sendwheelevent%28%29.

var windowutils = window.queryinterface(components.interfaces.nsiinterfacerequestor)                          .getinterface (components.interfaces.nsidomwindowutils);  windowutils.sendwheelevent(window.innerwidth / 2, window.innerheight / 2, 0, 10, 0,                            wheelevent.dom_delta_line, 0, 0, 0, 0); 

i'm still curious what's matter dispatchevent.

you can element position so:

var elem = document.elementfrompoint(content.innerwidth / 2, content.innerheight / 2); 

and apply scroll:

elem.scrolltop += 10;