JSFiddle - React, Tailwind, and code Playground

HTML

Alternate field:
<input id="dpAlt" readonly="true" />

Datepicker Input:
<input id="dp" />

CSS

input
{
    display: block;
    margin: 10px;
}

JavaScript

$( function() {
    $("#dp").datepicker({
        dateFormat: 'MM d, yy',
        altField: jQuery("#dpAlt"),
        altFormat: "yy-mm-dd"
    });
});