let sliders   = document.querySelectorAll('.swiper');

  sliders.forEach(slider => {
    let slider_id = slider.dataset.sliderid;
    let slides_per_view = slider.dataset.slidesperview;
  
  
  
    var swiper = new Swiper( '#' + slider_id , {
  
      loop: false,
      speed: 400,
      spaceBetween: 18,
      breakpoints: {
        320: {
          slidesPerView: 2,
        },
        // when window width is >= 640px
        640: {
          slidesPerView: 3,
        },
        980: {
          slidesPerView: slides_per_view,
        }
      },
  
      navigation: {
        nextEl: '#slidenext_' + slider_id,
        prevEl: '#slideback_' + slider_id,
      },
  
    });
  });