JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" class="date" />

JavaScript

function isDate(value) {
    var isDate = false;
    try {
        var dateFormat = "yy";
        $.datepicker.parseDate(dateFormat, value);
        isDate = true;
    } catch (e) {}
    return isDate;
}

$(".date").datepicker({dateFormat: 'yy'});
$(".date").change(function() {
    alert($(this).val() + " is a date? " + isDate($(this).val()));
});