Javascript - Dispatch built-in events [duplicate]

I know that we can use element.dispatchEvent(custom_event) to dispatch a custom event that we defined. My question is how to dispatch built-in events, such as submit, click, change, ...

I write form.on('submit', function(){}) to hanlde form submitting event. Then, I want to dispatch submit form by clicking on an X element.

X.on('click', function(){
    // dispatch form submit here
});

P/s: I'm using PrototyeJS