JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://jdpicker.paulds.fr/jquery.jdpicker.js"></script>
<div class="firstClass1" id="firstID1"> // suppose I start from this element
    <div class="secondClass1" id="secondID1">
        <input value="myValue1"/>
    </div>
</div>
<div class="firstClass2" id="firstID2">
    <div class="secondClass2" id="secondID2">
        <input value="myValue2"/>
    </div>
</div>
<div class="firstClass3" id="firstID3">
    <div class="secondClass3" id="secondID3">
        <input value="myValue3"/>
    </div>
</div>

JavaScript

var nextID = $('div#firstID1').next('div').find('input').val();
               
               
               alert(nextID);