Disable dates in year view

[reholmes27]

I can implement a setup where I select a start date and then disable prior dates in an end date input, however, if I try and do it with just the year and month setup, it doesn't disable previous months. Example:

let startDate = $('.sStartDate').fdatepicker({
startView: 'year',
minView: 'year',
format: "mm/yyyy",
closeButton: true,
closeIcon: '',
})
.on( 'changeDate', function(ev) {
selectedDate = new Date(ev.date);

    $('.sEndDate').fdatepicker({ 
	startDate: selectedDate,
	startView: 'year',
	minView: 'year',
	format: "mm/yyyy",
	onRender: function (date) {
		return date.valueOf() < selectedDate.valueOf() ? 'disabled' : '';
	}
});

})
.data('datepicker');