Slick.prototype.lazyLoad = function()

in assets/js/slick.js [1541:1647]
45 lines of code
13 McCabe index (conditional complexity)

    Slick.prototype.lazyLoad = function() {

        var _ = this,
            loadRange, cloneRange, rangeStart, rangeEnd;

        function loadImages(imagesScope) {

            $('img[data-lazy]', imagesScope).each(function() {

                var image = $(this),
                    imageSource = $(this).attr('data-lazy'),
                    imageSrcSet = $(this).attr('data-srcset'),
                    imageSizes  = $(this).attr('data-sizes') || _.$slider.attr('data-sizes'),
                    imageToLoad = document.createElement('img');

                imageToLoad.onload = function() {

                    image
                        .animate({ opacity: 0 }, 100, function() {

                            if (imageSrcSet) {
                                image
                                    .attr('srcset', imageSrcSet );

                                if (imageSizes) {
                                    image
                                        .attr('sizes', imageSizes );
                                }
                            }

                            image
                                .attr('src', imageSource)
                                .animate({ opacity: 1 }, 200, function() {
                                    image
                                        .removeAttr('data-lazy data-srcset data-sizes')
                                        .removeClass('slick-loading');
                                });
                            _.$slider.trigger('lazyLoaded', [_, image, imageSource]);
                        });

                };

                imageToLoad.onerror = function() {

                    image
                        .removeAttr( 'data-lazy' )
                        .removeClass( 'slick-loading' )
                        .addClass( 'slick-lazyload-error' );

                    _.$slider.trigger('lazyLoadError', [ _, image, imageSource ]);

                };

                imageToLoad.src = imageSource;

            });

        }

        if (_.options.centerMode === true) {
            if (_.options.infinite === true) {
                rangeStart = _.currentSlide + (_.options.slidesToShow / 2 + 1);
                rangeEnd = rangeStart + _.options.slidesToShow + 2;
            } else {
                rangeStart = Math.max(0, _.currentSlide - (_.options.slidesToShow / 2 + 1));
                rangeEnd = 2 + (_.options.slidesToShow / 2 + 1) + _.currentSlide;
            }
        } else {
            rangeStart = _.options.infinite ? _.options.slidesToShow + _.currentSlide : _.currentSlide;
            rangeEnd = Math.ceil(rangeStart + _.options.slidesToShow);
            if (_.options.fade === true) {
                if (rangeStart > 0) rangeStart--;
                if (rangeEnd <= _.slideCount) rangeEnd++;
            }
        }

        loadRange = _.$slider.find('.slick-slide').slice(rangeStart, rangeEnd);

        if (_.options.lazyLoad === 'anticipated') {
            var prevSlide = rangeStart - 1,
                nextSlide = rangeEnd,
                $slides = _.$slider.find('.slick-slide');

            for (var i = 0; i < _.options.slidesToScroll; i++) {
                if (prevSlide < 0) prevSlide = _.slideCount - 1;
                loadRange = loadRange.add($slides.eq(prevSlide));
                loadRange = loadRange.add($slides.eq(nextSlide));
                prevSlide--;
                nextSlide++;
            }
        }

        loadImages(loadRange);

        if (_.slideCount <= _.options.slidesToShow) {
            cloneRange = _.$slider.find('.slick-slide');
            loadImages(cloneRange);
        } else
        if (_.currentSlide >= _.slideCount - _.options.slidesToShow) {
            cloneRange = _.$slider.find('.slick-cloned').slice(0, _.options.slidesToShow);
            loadImages(cloneRange);
        } else if (_.currentSlide === 0) {
            cloneRange = _.$slider.find('.slick-cloned').slice(_.options.slidesToShow * -1);
            loadImages(cloneRange);
        }

    };