Modifying day names in specific views that use dayHeaderDidMount

Below is an example of how to use the piecal_additional_day_header_did_mount_js hook to modify the day names output in day headers. Note that this only works with views that utilize dayHeaderDidMount, such as dayGridMonth, timeGridWeek, and dayGridWeek.

add_action( 'piecal_additional_day_header_did_mount_js', function() {
	?>
	let dayHeaderLink = info.el.querySelector('a');
	
	let modifiableViews = ['dayGridMonth', 'timeGridWeek', 'dayGridWeek'];
	
	let customDayNames = [
		'First Day',
		'Second Day',
		'Third Day',
		'Fourth Day',
		'Fifth Day',
		'Sixth Day',
		'Seventh Day'
	];
	
	if( modifiableViews.includes( info.view.type ) ) {
		dayHeaderLink.innerText = customDayNames[info.dow];	
	}
	<?php
} );