JSFiddle - React, Tailwind, and code Playground

HTML

<div id="InsertDiv">
    <div draggable="true" onclick="openPropDyn(event)" data-serial="6018" ondragstart="drag(event,6018)" class="subtaskDetailDive complete" id="subtaskDetailDive6018">
        t1
        <div class="subtaskRow" id="readOnlyID6018">
            <textarea></textarea>
        </div>
    </div>
    <div draggable="true" onclick="openPropDyn(event)" data-serial="6019" ondragstart="drag(event,6019)" class="subtaskDetailDive complete" id="subtaskDetailDive6019">
        t2
        <div class="subtaskRow" id="readOnlyID6019">
            <textarea></textarea>
        </div>
    </div>
    <div draggable="true" onclick="openPropDyn(event)" data-serial="6020" ondragstart="drag(event,6020)" class="subtaskDetailDive complete" id="subtaskDetailDive6020">
        t3
        <div class="subtaskRow" id="readOnlyID6020">
            <textarea></textarea>
        </div>
    </div>
    <div draggable="true" onclick="openPropDyn(event)" data-serial="6021" ondragstart="drag(event,6021)" class="subtaskDetailDive complete" id="subtaskDetailDive6021">
        t4
        <div class="subtaskRow" id="readOnlyID6021">
            <textarea></textarea>
        </div>
    </div>
    <div draggable="true" onclick="openPropDyn(event)" data-serial="6022" ondragstart="drag(event,6022)" class="subtaskDetailDive complete" id="subtaskDetailDive6022">
        t5
        <div class="subtaskRow" id="readOnlyID6022">
            <textarea></textarea>
        </div>
    </div>
</div>

JavaScript

$('.subtaskRow textarea').on('keyup', function(e) {
    if(e.keyCode == 38){
      $(".subtaskRow textarea:focus").closest('.subtaskDetailDive').prev().find('.subtaskRow textarea').focus();
      console.log("Up key Pressed");
    }      
    else if(e.keyCode == 40){
      $(".subtaskRow textarea:focus").closest('.subtaskDetailDive').next().find('.subtaskRow textarea').focus();
      console.log("Down key Pressed");
    }
});