trigger custom event without jQuery

Answer 1

You can use Custom Events and dispatch them on element you want.

Answer 2

If you want an exact replication of jQuery's behaviour, you're probably best off digging through the jQuery source code.

If you just want to do normal event dispatching and listening, see CustomEvent for how to dispatch an event with custom data and addEventListener for how to listen to it.

Your example would probably look something like

document.addEventListener('hey', function(customEvent)
{
    console.log(customEvent.type + ' ' + customEvent.detail.user); // hey stackoverflow
});
document.dispatchEvent(new CustomEvent('hey', {'detail': {'user': 'stackoverflow'}}));