Stole

var scroller=$("#scroller");function scrollL(){$(".scroller").width();scroller.animate({scrollLeft:"+=400"},250)}function scrollR(){scroller.animate({scrollLeft:"-=400"},250)}function checkNav(){scroller.scroll(function(){var e=Math.ceil(scroller.outerWidth()),l=scroller[0].scrollWidth,r=scroller.scrollLeft(),c=$("#slideRight"),s=$("#slideLeft");Math.ceil(l-e)===r?s.addClass("deactivated"):s.removeClass("deactivated"),0===r?c.addClass("deactivated"):c.removeClass("deactivated")}),scroller.prop("scrollWidth")>scroller.width()&&$("#slideLeft").removeClass("deactivated")}checkNav(),addEventListener("resize",e=>{checkNav()});