JSFiddle - React, Tailwind, and code Playground

HTML

<form id="frm_nm_chx_exp" name="id_chx_exp" action="http://www.google.fr" method="post" >
          <input type="checkbox" id="id_ass_oui"> Assurance ?
          <input type="hidden" id="autre">
          <input type="submit" name="foo" value="valider" > 
          </form>

JavaScript

$(function(){

$('#frm_nm_chx_exp').on("submit", function(){ 
              if(document.getElementById('id_ass_oui').checked == false) {
                return confirm("Validez vous malgré l'absence d'assurance assurance ?");
                              }
              else {
                return true;
              }
            })

});