$('#registerInputUsername1') .change(function(e) { var inputUsername = $(this); var username = inputUsername.val(); var re = /^[A-Za-z][A-Za-z0-9_]+$/; var isUsernameValid = username.match(re); if(! isUsernameValid) { inputUsername .addClass('is-invalid') .removeClass('is-valid'); return; } $.get( 'http://localhost:3001/username-check?username=' + username, function(response) { console.log(response.success) if(response.success) { inputUsername .addClass('is-valid') .removeClass('is-invalid'); } else { inputUsername .addClass('is-invalid') .removeClass('is-valid'); return; } } ); }); var onglets = $('#onglets li a'); onglets.click(function(e) { var link = $(this); onglets.removeClass('active'); link.addClass('active'); var idPanneau = link.data('tab-id'); $('.tab').hide(); $('#' + idPanneau).show(); });