Run two functions on the same click button

Question

I want to change my code in order to run the functions setMeansForm and setAtaGrpForm at the same time and on the same button. I want to keep the same logic, but it seems that's not working when i try to call each function on the same button (btnContinueMeans). I know i have to create an intermediate function to run both functions at the same time but i don't know how and i try to keep the current logic of the script.

Here the code i tried :

<script>

      function setMeansForm(means) {
        // Set input
        setMultiSelectInput(means, '#inputMeans', '#datalistMeans', 'ul#displayMeans');
        // Set button
        const btnApply = document.querySelector('#btnApplyMeans');
        const divContinue = document.querySelector('#continueMeans');
        const btnContinue = document.querySelector('#btnContinueMeans');
        btnApply.onclick = () => {
          btnApply.style.display = 'none';
          divContinue.style.display = '';
        }
        btnContinue.onclick = () => {
          btnContinue.disabled = true;
          new Promise((resolve, reject) => {
            google.script.run
            .withFailureHandler(reject)
            .withSuccessHandler(resolve)
            .setMeans(getItemSelected('ul#displayMeans'));
          }).then(() => {
            btnApply.style.display = '';
            divContinue.style.display = 'none';
            btnContinue.disabled = false;
          });
        }
      }

      /**
       * Set behavior and data of the Ata Grp form
       */
      function setAtaGrpForm(ata_grp) {
        // Set input
        setMultiSelectInput(ata_grp, '#inputAtaGrp', '#datalistAtaGrp', 'ul#displayAtaGrp');
        // Set button
        const btnApply = document.querySelector('#btnApplyMeans');
        const divContinue = document.querySelector('#continueMeans');
        const btnContinue = document.querySelector('#btnContinueMeans');
        btnApply.onclick = () => {
          btnApply.style.display = 'none';
          divContinue.style.display = '';
        }
        btnContinue.onclick = () => {
          btnContinue.disabled = true;
          new Promise((resolve, reject) => {
            google.script.run
            .withFailureHandler(reject)
            .withSuccessHandler(resolve)
            .setAtaGrp(getItemSelected('ul#displayAtaGrp'));
          }).then(() => {
            btnApply.style.display = '';
            divContinue.style.display = 'none';
            btnContinue.disabled = false;
          });
        }
      }
    </script>