Add Previous Next to Slide from Current Slide

setInterval(function(){ 
jQuery('span.swiper-pagination-bullet').removeClass('prev_slide');
jQuery('span.swiper-pagination-bullet').removeClass('next_slide');	
var previous = jQuery('span.swiper-pagination-bullet.swiper-pagination-bullet-active').prev();
        if(previous.length == 0){
             previous = jQuery('.swiper-pagination-clickable.swiper-pagination-bullets .swiper-pagination-bullet').last();   
        }
        previous.addClass('prev_slide');
         var next = jQuery('span.swiper-pagination-bullet.swiper-pagination-bullet-active').next();
        if(next.length == 0){
           next = jQuery('.swiper-pagination-clickable.swiper-pagination-bullets .swiper-pagination-bullet').first();
        }
         next.addClass('next_slide');
}, 1500);
 //OR
  setInterval(function(){ 
jQuery('span.swiper-pagination-bullet').removeClass('prev_slide');
jQuery('span.swiper-pagination-bullet').removeClass('next_slide');	
jQuery('span.swiper-pagination-bullet.swiper-pagination-bullet-active').prev().addClass('prev_slide');
  jQuery('span.swiper-pagination-bullet.swiper-pagination-bullet-active').next().addClass('next_slide');
}, 2500);