https://css.renrendoc.com/JS/jquery.lazyload.js?v=20230320

1/*
2 * Lazy Load - jQuery plugin for lazy loading images
3 *
4 * Copyright (c) 2007-2013 Mika Tuupola
5 *
6 * Licensed under the MIT license:
7 *   http://www.opensource.org/licenses/mit-license.php
8 *
9 * Project home:
10 *   http://www.appelsiini.net/projects/lazyload
11 *
12 * Version:  1.9.3
13 *
14 */
15
16(function ($, window, document, undefined) {
17    var $window = $(window);
18
19    $.fn.lazyload = function (options) {
20        var elements = this;
21        var $container;
22        var settings = {
23            threshold: 0,
24            failure_limit: 0,
25            event: "scroll",
26            effect: "show",
27            container: window,
28            data_attribute: "original",
29            skip_invisible: true,
30            appear: null,
31            load: null,
32            placeholder: "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB/AAffA0nNPuCLAAAAAElFTkSuQmCC"
33        };
34
35        function update() {
36            var counter = 0;
37
38            elements.each(function () {
39                var $this = $(this);
40                if (settings.skip_invisible && !$this.is(":visible")) {
41                    return;
42                }
43                if ($.abovethetop(this, settings) ||
44                    $.leftofbegin(this, settings)) {
45                    /* Nothing. */
46                } else if (!$.belowthefold(this, settings) &&
47                    !$.rightoffold(this, settings)) {
48                    $this.trigger("appear");
49                    /* if we found an image we'll load, reset the counter */
50                    counter = 0;
51                } else {
52                    if (++counter > settings.failure_limit) {
53                        return false;
54                    }
55                }
56            });
57
58        }
59
60        if (options) {
61            /* Maintain BC for a couple of versions. */
62            if (undefined !== options.failurelimit) {
63                options.failure_limit = options.failurelimit;
64                delete options.failurelimit;
65            }
66            if (undefined !== options.effectspeed) {
67                options.effect_speed = options.effectspeed;
68                delete options.effectspeed;
69            }
70
71            $.extend(settings, options);
72        }
73
74        /* Cache container as jQuery as object. */
75        $container = (settings.container === undefined ||
76                      settings.container === window) ? $window : $(settings.container);
77
78        /* Fire one scroll event per scroll. Not one scroll event per image. */
79        if (0 === settings.event.indexOf("scroll")) {
80            $container.bind(settings.event, function () {
81                return update();
82            });
83        }
84
85        this.each(function () {
86            var self = this;
87            var $self = $(self);
88
89            self.loaded = false;
90
91            /* If no src attribute given use data:uri. */
92            if ($self.attr("src") === undefined || $self.attr("src") === false) {
93                if ($self.is("img")) {
94                    $self.attr("src", settings.placeholder);
95                }
96            }
97
98            /* When appear is triggered load original image. */
99            $self.one("appear", function () {
100                if (!this.loaded) {
101                    if (settings.appear) {
102                        var elements_left = elements.length;
103                        settings.appear.call(self, elements_left, settings);
104                    }
105                    $("<img />")
106                        .bind("load", function () {
107
108                            var original = $self.attr("data-" + settings.data_attribute);
109                            $self.hide();
110                            if ($self.is("img")) {
111                                $self.attr("src", original);
112                            } else {
113                                $self.css("background-image", "url('" + original + "')");
114                            }
115                            $self[settings.effect](settings.effect_speed);
116
117                            self.loaded = true;
118
119                            /* Remove image from array so it is not looped next time. */
120                            var temp = $.grep(elements, function (element) {
121                                return !element.loaded;
122                            });
123                            elements = $(temp);
124
125                            if (settings.load) {
126                                var elements_left = elements.length;
127                                settings.load.call(self, elements_left, settings);
128                            }
129                        })
130                        .bind("error", function(e) {
131                            $self.addClass("lazy-error");
132                        })
133                        .attr("src", $self.attr("data-" + settings.data_attribute));
134                }
135            });
136
137            /* When wanted event is triggered load original image */
138            /* by triggering appear.                              */
139            if (0 !== settings.event.indexOf("scroll")) {
140                $self.bind(settings.event, function () {
141                    if (!self.loaded) {
142                        $self.trigger("appear");
143                    }
144                });
145            }
146        });
147
148        /* Check if something appears when window is resized. */
149        $window.bind("resize", function () {
150            update();
151        });
152
153        /* With IOS5 force loading images when navigating with back button. */
154        /* Non optimal workaround. */
155        if ((/(?:iphone|ipod|ipad).*os 5/gi).test(navigator.appVersion)) {
156            $window.bind("pageshow", function (event) {
157                if (event.originalEvent && event.originalEvent.persisted) {
158                    elements.each(function () {
159                        $(this).trigger("appear");
160                    });
161                }
162            });
163        }
164
165        /* Force initial check if images should appear. */
166        $(document).ready(function () {
167            update();
168        });
169
170        return this;
171    };
172
173    /* Convenience methods in jQuery namespace.           */
174    /* Use as  $.belowthefold(element, {threshold : 100, container : window}

174) */
175
176    $.belowthefold = function (element, settings) {
177        var fold;
178
179        if (settings.container === undefined || settings.container === window) {
180            fold = (window.innerHeight ? window.innerHeight : $window.height()) + $window.scrollTop();
181        } else {
182            fold = $(settings.container).offset().top + $(settings.container).height();
183        }
184
185        return fold <= $(element).offset().top - settings.threshold;
186    };
187
188    $.rightoffold = function (element, settings) {
189        var fold;
190
191        if (settings.container === undefined || settings.container === window) {
192            fold = $window.width() + $window.scrollLeft();
193        } else {
194            fold = $(settings.container).offset().left + $(settings.container).width();
195        }
196
197        return fold <= $(element).offset().left - settings.threshold;
198    };
199
200    $.abovethetop = function (element, settings) {
201        var fold;
202
203        if (settings.container === undefined || settings.container === window) {
204            fold = $window.scrollTop();
205        } else {
206            fold = $(settings.container).offset().top;
207        }
208
209        return fold >= $(element).offset().top + settings.threshold + $(element).height();
210    };
211
212    $.leftofbegin = function (element, settings) {
213        var fold;
214
215        if (settings.container === undefined || settings.container === window) {
216            fold = $window.scrollLeft();
217        } else {
218            fold = $(settings.container).offset().left;
219        }
220
221        return fold >= $(element).offset().left + settings.threshold + $(element).width();
222    };
223
224    $.inviewport = function (element, settings) {
225        return !$.rightoffold(element, settings) && !$.leftofbegin(element, settings) &&
226               !$.belowthefold(element, settings) && !$.abovethetop(element, settings);
227    };
228
229    /* Custom selectors for your convenience.   */
230    /* Use as $("img:below-the-fold").something() or */
231    /* $("img").filter(":below-the-fold").something() which is faster */
232
233    $.extend($.expr[":"], {
234        "below-the-fold": function (a) { return $.belowthefold(a, { threshold: 0 }); },
235        "above-the-top": function (a) { return !$.belowthefold(a, { threshold: 0 }); },
236        "right-of-screen": function (a) { return $.rightoffold(a, { threshold: 0 }); },
237        "left-of-screen": function (a) { return !$.rightoffold(a, { threshold: 0 }); },
238        "in-viewport": function (a) { return $.inviewport(a, { threshold: 0 }); },
239        /* Maintain BC for couple of versions. */
240        "above-the-fold": function (a) { return !$.belowthefold(a, { threshold: 0 }); },
241        "right-of-fold": function (a) { return $.rightoffold(a, { threshold: 0 }); },
242        "left-of-fold": function (a) { return !$.rightoffold(a, { threshold: 0 }); }
243    });
244
245})(jQuery, window, document);