var doubleSlider = document.querySelectorAll('.double-slider');
var pagePer = (window.innerWidth <= 768) ? 1 : 2;
if(doubleSlider.length){
    doubleSlider.forEach(function(e){
         var double = new Splide( '#'+e.id, {
            type:'loop',
            autoplay:true,
            interval:4000,
            arrows:false,
            perPage: pagePer,
        }).mount();
    });