JSFiddle - React, Tailwind, and code Playground

HTML

<body>
        <div id="bouton">
            <input type="button" name="bouton" value="Notation" />
        </div>
    </body>

JavaScript

(function(){
    var exemple = {
        init : function(){
            window.addEventListener('load',function(event){
               var bouton = document.getElementById('bouton');
                bouton.addEventListener('click',function(event){                
                    if (!document.getElementById('formulaire')){                    
                        var form = document.createElement('form');
                        form.action='devoir_2_demande_2.php';
                        form.id='formulaire';
                        form.method='POST';
                        var select = document.createElement('select');
                        select.id = 'choice';
                        select.name='note_classique';
                        form.appendChild(select);
                        document.body.appendChild(form);
         
                        // Génération du tableau de corrspondance des notes de musique
         
                        var notes = [['Faites votre choix', 'Do', 'Ré', 'Mi', 'Fa', 'Sol', 'La', 'Si'], ['', 'C', 'D', 'E', 'F', 'G', 'A', 'B']];
         
                        notes[0].forEach(function(valeur,index){
                           var option = new Option(valeur,index);
                        select.appendChild(option);
                        });
                        
                    }        
                        
                });
            });
        }
    };
    exemple.init();
})();