JavaScript Uncaught TypeError: Cannot read property 'style' of null: Onclick makes page disappear

Question

In a django project, I've set up a JavaScript function to select/block certain pages. I have another JavaScript function for the pages that are being loaded. This function has an onclick event listener that submits text to a form field. The problem I'm having is that when I click a button to add text to a form field, the entire page disappears. The exact error message showing in the console is...

Uncaught TypeError: Cannot read property 'style' of null
    at showPage (players:6382)
    at HTMLButtonElement.button.onclick (players:6388)

Here's the function controlling showing/blocking of individual pages.

 function showPage(page) {
        document.querySelectorAll('tbody').forEach(tbody => {tbody.style.display = 'none';})

        document.querySelector(`#${page}`).style.display = 'table-row-group'; ---(This line in error message)
    }

    document.addEventListener('DOMContentLoaded', function() {
        document.querySelectorAll('button').forEach(button => {
            button.onclick = function() {
                showPage(this.dataset.page); ---(This line in error message)
            }           
        });
    });

Here's an example from the html template of a button targeted by this function.

<button class="posbutton" data-page="page1">QB</button>

This is the function that submits text to a form field.

function myFunction(txt) {
          var myTxt = txt;
      
          
          if (txt.includes('QB')) {
              document.getElementById("QB_name").value = myTxt;
          }

          else if (txt.includes('RB')) {
              document.getElementById("RB_name").value = myTxt;
          }

          else if (txt.includes('WR')) {
              document.getElementById("WR_name").value = myTxt;
          }

          else if (txt.includes('TE')) {
              document.getElementById("TE_name").value = myTxt;
          }

          else if (txt.includes('K')) {
              document.getElementById("K_name").value = myTxt;
          }
          
      }

Here's an example of the html element targetted by the showPage function. It also contains a line with the button that's linked to the myFunction for submitting text.

<tbody id="page1">
               
         {% for q in QBpage %}
              <tr>
                <th scope="row">
                      
                </th>
                    
                <td><h6>{{ q.player_name }}</h6></td>
                <td><input type="button"  class="btn btn-outline-primary btn-sm m-0 waves-effect" onclick="myFunction('{{ player_data.player_name }} {{ player_data.position }}')">Add</input></td>
                <td><h6> {{ q.team }} </h6></td>
                <td><h6> {{ q.position }}  </h6></td>
                <td><h6>{{ q.points }}</h6></td>
                </tr>
                  
         {% endfor %}
</tbody>

I've looked around at similar questions and tried positioning my tags just before the {% endblock %} tag in the html template, but no good. I've also tried positioning the scripts at the start of the template. As a JavaScript novice, I'm not sure where else to look and would really appreciate any opinions on where I'm going wrong here.

JavaScript Uncaught TypeError: Cannot read property 'style' of null: Onclick makes page disappear

0 Answers0