JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.4.0/js/bootstrap-datepicker.min.js"></script>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/bootstrap-datepicker/1.4.0/css/bootstrap-datepicker.css">
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<p>&nbsp;</p>
<div class="row">
    <div class="col-xs-6">
        <div class="form-group">
            <label class="control-label">Start</label>
            <input class="form-control" type="text" placehoder="Start Date" id="startDate" />
        </div>
    </div>
    <div class="col-xs-6">
        <div class="form-group">
            <label class="control-label">End</label>
            <input class="form-control" type="text" placehoder="End Date" id="endDate" />
        </div>
    </div>
</div>

<pre id="output"></pre>

JavaScript

$(document).ready(function() {

    $("#startDate").datepicker({
        todayBtn: true,
        autoclose: true,
        clearBtn: true
    }).on('changeDate', function(selected) {
        var endDate_Bottom = new Date(selected.date.valueOf());
        var endDate_Cap = new Date(selected.date.valueOf());
        // if the selected start date is in [Oct, Nov, Dec] then set the endDate cap to
        //	the end of the next year's Sept.
        if (endDate_Bottom.getMonth() >= 9 && endDate_Bottom.getMonth() <= 11) {
            endDate_Cap = new Date(endDate_Bottom.getFullYear() + 1, 8, 30);
        }
        // if the selected start date is not in [Oct, Nov, Dec] set the endDate cap
        // 	to Sept. of the selected start date's year
        else {
            endDate_Cap = new Date(endDate_Bottom.getFullYear(), 8, 30);
        }
        out("endDate_Bottom is: ", endDate_Bottom)
        out("endDate_Cap is: ", endDate_Cap)
        $('#endDate').datepicker('setStartDate', endDate_Bottom);
        $('#endDate').datepicker('setEndDate', endDate_Cap);
    });

    $("#endDate").datepicker({
        todayBtn: true,
        autoclose: true,
        clearBtn: true
    }).on('changeDate', function(selected) {
        var startDate_Cap = new Date(selected.date.valueOf());
        $('#startDate').datepicker('setEndDate', startDate_Cap);
    });

    function out() {
        var args = Array.prototype.slice.call(arguments, 0);
        document.getElementById('output').innerHTML += args.join(" ") + "\n";
    }

    out("Hello world!");
});