stripe.createSource(card).then(function(result) {
      if (result.error) {
        formIsPending = false;
        // Inform the user if there was an error
        var errorElement = document.getElementById('card-errors');
        errorElement.textContent = result.error.message;
      } else {
        // Send the source to your server
        stripeSourceHandler(result.source);
      }
    });