Rinser/html/js/jquery.unveil.js

/**
 * jQuery Unveil
 * A very lightweight jQuery plugin to lazy load images
 * http://luis-almeida.github.com/unveil
 *
 * Licensed under the MIT license.
 * Copyright 2013 Luís Almeida
 * https://github.com/luis-almeida
 */

;
(function($) {

        var blackList = ['feeds.feedburner.com', '.feedsportal.co'];
        $.fn.unveil = function(threshold, callback) {

            var $w = $(window),
                th = threshold || 0,
                retina = window.devicePixelRatio > 1,
                attrib = retina ? "data-src-retina" : "data-src",
                images = this,
                loaded;

            this.one("unveil", function() {
                    var source = this.getAttribute(attrib);
                    source = source || this.getAttribute("data-src");

                    var flag = false;
                    for (var item in blackList) {
                        var u = blackList[item];
                        if (source.indexOf(u) !== -1) {
                                flag = true;
                            }
                        }

                        if (source && !flag) {

                          if (!S(source).startsWith('http')) {
                            source = 'http://' + S(source).stripLeft('/').s;
                               }
                          source = 'http://image.silvrtree.co.uk/1140,fit,q80/' + source;

                            this.setAttribute("src", source);
                            if (typeof callback === "function") callback.call(this);
                        }

                        if (flag) {
                            this.setAttribute("style", 'display:none !important;');
                        }
                    });

                function unveil() {
                    var inview = images.filter(function() {
                        var $e = $(this);
                        //    if ($e.is(":hidden")) return;

                        var wt = $w.scrollTop(),
                            wb = wt + $w.height(),
                            et = $e.offset().top,
                            eb = et + $e.height();

                        return eb >= wt - th && et <= wb + th;
                    });

                    loaded = inview.trigger("unveil");
                    images = images.not(loaded);
                }

                $w.on("scroll.unveil resize.unveil lookup.unveil", unveil);

                unveil();

                return this;

            };

        })(window.jQuery || window.Zepto);