No idea what you asking
''play emulator online'' (via browser) sounds like the java based emulators that can be found at some web sites, to use your controller with those you would need to convert joypad presses into keyboard presses, this does also require you to have java installed
http://www.emuparadise.me/playonline.php is that what you are talking about
You just select what you want to play nothing else needed keyboard controls are listed above the game, just wait for it to load
Your security settings may be blocking it though, but like I said it's not worth using at all honesty