in slick/slick.js [2552:2571]
Slick.prototype.updateDots = function() {
var _ = this;
if (_.$dots !== null) {
_.$dots
.find('li')
.removeClass('slick-active')
.attr('aria-hidden', 'true');
_.$dots
.find('li')
.eq(Math.floor(_.currentSlide / _.options.slidesToScroll))
.addClass('slick-active')
.attr('aria-hidden', 'false');
}
};