javascript - Uncaught ReferenceError: update_zone is not defined

one text

When I select a country, the zone must be displayed on dropdown after to click on a selected country dropdown. But in my case, I have this error come from console :

Uncaught ReferenceError: update_zone is not defined

below my code

my state_dropdown.php (js)

`

<script>
  function resetZoneSelected(theForm) {
    if (theForm.state.value != '') {
      theForm.state.selectedIndex = '0';
      if (theForm.state.options.length > 0) {
        theForm.state.value = '<?php echo CLICSHOPPING::getDef('js_state_select'); ?>';
      }
    }
  }

  function update_zone(theForm) {
      let NumState = theForm.state.options.length;
      let SelectedCountry = "";

      while(NumState > 0) {
      NumState--;
      theForm.state.options[NumState] = null;
    }

    SelectedCountry = theForm.country.options[theForm.country.selectedIndex].value;

    <?php echo HTMLOverrideAdmin::getJsZoneList('SelectedCountry', 'theForm', 'state'); ?>

  }
  </script>

my code to call that.

<?php echo HTML::selectMenuCountryList('country', null, 'onchange="update_zone(this.form);" aria-required="true"'); ?>

I select form example France

<?php echo HTML::selectField('state', $Address->getPrepareCountryZonesPullDown(), null, 'aria-required="true"'); ?>

In this case inside my dropdown, I must See a state as Var for example. But this case does no work. I have nothing

and at the end :

include_once('javascript/state_dropdown.php');

The code below does not work and I have Uncaught ReferenceError: update_zone is not defined

Thank you