P.when(“jQuery”, “ready”).execute(function($) {

"use strict";

$('.single-field-form-submit-button').click(function(event) {
      var form = $(this).closest('.single-field-form');
  testEmail(form) ? form.submit() : displayErrorMessage(form);
});

$('.single-field-form-email-input').on('keyup keypress', function(e) {
  // Enter key
  if (e.keyCode === 13) {
    e.preventDefault();
    var form = $(this).closest('.single-field-form');
    testEmail(form) ? form.submit() : displayErrorMessage(form);
    return false;
  }
});

function testEmail(form) {
      var email = form.find('.single-field-form-email-input').val();
  var testEmail = /^[A-Z0-9._%+-]+@([A-Z0-9-]+\.)+[A-Z]{2,4}$/i;  // jshint ignore:line
  return testEmail.test(email);
}

function displayErrorMessage(form) {
  form.find('.a-alert-error').css("display", "block");
}

});