JSFiddle - React, Tailwind, and code Playground

HTML

<label for="from">From</label>
<input type="text" id="from" name="from" />
<label for="to">to</label>
<input type="text" id="to" name="to" />

JavaScript

$(function() {
$( "#from" ).datepicker({
defaultDate: "+1w",
changeMonth: true,
numberOfMonths: 3,
onClose: function( selectedDate ) {
$( "#to" ).datepicker( "option", "minDate", selectedDate );
}
});
$( "#to" ).datepicker({
defaultDate: "+1w",
changeMonth: true,
numberOfMonths: 3,
onClose: function( selectedDate ) {
$( "#from" ).datepicker( "option", "maxDate", selectedDate );
}
});
});

$("#to").change( function() {
var final = $("#to").datepicker( "getDate" );
    var start = $("#from").datepicker( "getDate" );
    var dias = new Date(final - start);

    alert(days);
});