JavaScript: How to pass multiple parameters (and the event object) to an event handler

If we just wanted to pass the event object from an event listener to an event handler, this could be done without setting any parameters.

For example:

mobileInput.addEventListener('keydown', validateMobile);

function validateMobile(event) {
	const keyCode = event.which ? event.which : event.keyCode;

	// etc.
}

But what if, besides the event object, we also want to pass another parameter?

This can be done easily. And with an arrow function - also while keeping the code clean:

mobileInput.addEventListener('keydown', (event) =>
	validateMobile(event, anotherParam)
);

function validateMobile(event, anotherParam) {
	// Both the event object and anotherParam are available.
}