you can set it as value

var selectElement = $('#date-time');
var date = '2020-03-19'; // default date

selectElement.on('change', (event) => {
    date = selectElement.val().split('T')[0];
    selectElement.attr('value', date+'T22:00"');
});

I have a datetime-local input (and jQuery) and I’m trying to figure out how I can essentially autofill the time of the input. The value is not required so I can’t just set a default datetime, but I need the time to default to a predetermined time (let’s say 10:00 PM) if a user picks a date. (Other times are valid but extremely rare)

I tried to pull the incomplete value, but that appears to be impossible due to W3C’s sanitation of the value (per this SO thread and testing)

Is this even possible or will I need to abandon datetime-local?