add hidden variable value to the session without form submission

Question

i have a basic html table with some data displayed, what i want is when i click on specific row the value of incident Id cell is passed to the hidden variable value i have developed this part, what i don't know how can i put hidden variable value in the session for other functionality purposes.

my table

 <div id="tab1" class="tab active">
   <table class="table table-striped">
      <thead style="background-color: #F0F1F2">
           <tr>
            <th>Incident Id</th>
            <th>Party Name</th>
            <th>Max Rank</th>
            <th>Incident Description</th>
           </tr>
       </thead>
       <tbody>
         <c:forEach items="${incidents}" var="incident">
                                <tr id="tr" onclick="changeIncidentValue(${incident.incidentId})">                                
                                <td>${incident.incidentId}</td>
                                <td>xxx</td>
                                <td>${incident.partyNameMaxRank}</td>
                                <td>${incident.incidentDesc}</td>
                            </tr>
                            </c:forEach>                           
                        </tbody>
                    </table>
                </div>
                <input type="hidden" id="incidentId" name="incidentId" value=""/>

js function

<script>
    function changeIncidentValue(incidentId){  
        $('#incidentId').val(incidentId);
        var x = $('#incidentId').val();
        console.log(x);
    }
</script>