swiper-wait.js

(function() {
  function wait() {
    if (window.Swiper) {
      clearInterval(timer);
      var swiper = new Swiper ('.swiper-container', {
          direction: 'horizontal',
          loop: true,
          pagination: '.swiper-pagination',
          nextButton: 'nav .next',
          prevButton: 'nav .prev',
      });
    }
  }

  var timer = setInterval(wait, 100);
})();