两种图片延迟加载的方法总结jquery.scrollLoading.js与jquery.lazyload.js
估计网上能查到的最多的两种图片延迟加载方法就是jquery.scrollLoading.js与jquery.lazyload.js了，其中jquery.lazyload.js的调用方法因为有网友爆出的bug，改进了调用方法，另外修改了关于浏览器IE版本的判断。以下直接为代码，并没有什么修改。做个记号。
两种方法都采用jquery-1.8.3.min.js版本。
jquery.scrollLoading方法
html
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title></title> <script src="js/jquery-1.8.3.min.js"></script> <script src="Scripts/jquery.scrollLoading.js"></script> <script> $(function(){ $(".scrollLoading").scrollLoading(); }); </script> </head> <body> <h2>页面图片等元素滚动动态加载技术</h2> <br /> <img class="scrollLoading" data-url="images/mm/00_00.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_01.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_02.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_03.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_04.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_05.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_06.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_07.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_08.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> <br /><br /><br /><br /><br /><br /> <img class="scrollLoading" data-url="images/mm/00_09.jpg" src="images/pixel.gif" width="630" height="420" style="background:url(images/loading.gif) no-repeat center;" /> </body> </html>
js
/*! * jquery.scrollLoading.js * by zhangxinxu http://www.zhangxinxu.com/wordpress/?p=1259 * 2010-11-19 v1.0 * 2012-01-13 v1.1 偏移值计算修改 position → offset * 2012-09-25 v1.2 增加滚动容器参数, 回调参数 * 2014-08-11 v1.3 修复设置滚动容器参数一些bug, 以及误删posb值的一些低级错误 */ (function($) { $.fn.scrollLoading = function(options) { var defaults = { attr: "data-url", container: $(window), callback: $.noop }; var params = $.extend({}, defaults, options || {}); params.cache = []; $(this).each(function() { var node = this.nodeName.toLowerCase(), url = $(this).attr(params["attr"]); //重组 var data = { obj: $(this), tag: node, url: url }; params.cache.push(data); }); var callback = function(call) { if ($.isFunction(params.callback)) { params.callback.call(call.get(0)); } }; //动态显示数据 var loading = function() { var contHeight = params.container.height(); if (params.container.get(0) === window) { contop = $(window).scrollTop(); } else { contop = params.container.offset().top; } $.each(params.cache, function(i, data) { var o = data.obj, tag = data.tag, url = data.url, post, posb; if (o) { post = o.offset().top - contop, posb = post + o.height(); if ((post >= 0 && post < contHeight) || (posb > 0 && posb <= contHeight)) { if (url) { //在浏览器窗口内 if (tag === "img") { //图片，改变src callback(o.attr("src", url)); } else { o.load(url, {}, function() { callback(o); }); } } else { // 无地址，直接触发回调 callback(o); } data.obj = null; } } }); }; //事件触发 //加载完毕即执行 loading(); //滚动执行 params.container.bind("scroll", loading); }; })(jQuery);
jquery.lazyload.js方法
html
<!DOCTYPE html> <html xmlns="http://www.w3.org/1999/xhtml"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8"/> <title></title> <script src="js/jquery-1.8.3.min.js"></script> <script src="js/jquery.lazyload.js"></script> <script> function checkbrowse() { var ua = navigator.userAgent.toLowerCase(); var is = (ua.match(/\b(chrome|opera|safari|msie|firefox)\b/) || ['', 'mozilla'])[1]; var r = '(?:' + is + '|version)[\\/: ]([\\d.]+)'; var v = (ua.match(new RegExp(r)) || [])[1]; jQuery.browser.is = is; jQuery.browser.ver = v; return { 'is': jQuery.browser.is, 'ver': jQuery.browser.ver } } var public = checkbrowse(); var showeffect = ""; if ((public['is'] == 'msie' && public['ver'] < 8.0)) { showeffect = "show" } else { showeffect = "fadeIn" } $(function(){ $("img").lazyload({ threshold : 200, effect : showeffect }); }); </script> </head> <body> <h2>页面图片等元素滚动动态加载技术</h2> <br /> <img original="images/mm/1.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/2.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/3.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/4.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/5.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/6.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/7.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/8.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/9.jpg" src="images/loading.gif" width="630" height="420" /> <br /><br /><br /><br /><br /><br /> <img original="images/mm/10.jpg" src="images/loading.gif" width="630" height="420" /> </body> </html>
js
/* * Lazy Load - jQuery plugin for lazy loading images * * Copyright (c) 2007-2009 Mika Tuupola * * Licensed under the MIT license: * http://www.opensource.org/licenses/mit-license.php * * Project home: * http://www.appelsiini.net/projects/lazyload * * Version: 1.5.0 * */ (function ($) {
//判断客户端浏览器 function checkbrowse() { var ua = navigator.userAgent.toLowerCase(); var is = (ua.match(/\b(chrome|opera|safari|msie|firefox)\b/) || ['', 'mozilla'])[1]; var r = '(?:' + is + '|version)[\\/: ]([\\d.]+)'; var v = (ua.match(new RegExp(r)) || [])[1]; jQuery.browser.is = is; jQuery.browser.ver = v; return { 'is': jQuery.browser.is, 'ver': jQuery.browser.ver } } var public = checkbrowse(); $.fn.lazyload = function (options) { var showeffect = ""; if ((public['is'] == 'msie' && public['ver'] < 8.0)) { showeffect = "show"; } else { showeffect = "fadeIn"; } var settings = { threshold: 0, failurelimit: 0, event: "scroll", effect: showeffect, container: window }; if (options) { $.extend(settings, options); } /* Fire one scroll event per scroll. Not one scroll event per image. */ var elements = this; if ("scroll" == settings.event) { $(settings.container).bind("scroll", function (event) { var counter = 0; elements.each(function () { if ($.abovethetop(this, settings) || $.leftofbegin(this, settings)) { /* Nothing. */ } else if (!$.belowthefold(this, settings) && !$.rightoffold(this, settings)) { $(this).trigger("appear"); } else { if (counter++ > settings.failurelimit) { return false; } } }); /* Remove image from array so it is not looped next time. */ var temp = $.grep(elements, function (element) { return !element.loaded; }); elements = $(temp); }); } this.each(function () { var self = this; //删除的代码 /* When appear is triggered load original image. */ $(self).one("appear", function () { if (!this.loaded) { $("<img />").bind("load", function () { $(self).hide().attr("src", $(self).attr("original"))[settings.effect](settings.effectspeed); self.loaded = true; }).attr("src", $(self).attr("original")); }; }); /* When wanted event is triggered load original image */ /* by triggering appear. */ if ("scroll" != settings.event) { $(self).bind(settings.event, function (event) { if (!self.loaded) { $(self).trigger("appear"); } }); } }); /* Force initial check if images should appear. */ $(settings.container).trigger(settings.event); return this; }; /* Convenience methods in jQuery namespace. */ /* Use as $.belowthefold(element, {threshold : 100, container : window}) */ $.belowthefold = function (element, settings) { if (settings.container === undefined || settings.container === window) { var fold = $(window).height() + $(window).scrollTop(); } else { var fold = $(settings.container).offset().top + $(settings.container).height(); } return fold <= $(element).offset().top - settings.threshold; }; $.rightoffold = function (element, settings) { if (settings.container === undefined || settings.container === window) { var fold = $(window).width() + $(window).scrollLeft(); } else { var fold = $(settings.container).offset().left + $(settings.container).width(); } return fold <= $(element).offset().left - settings.threshold; }; $.abovethetop = function (element, settings) { if (settings.container === undefined || settings.container === window) { var fold = $(window).scrollTop(); } else { var fold = $(settings.container).offset().top; } return fold >= $(element).offset().top + settings.threshold + $(element).height(); }; $.leftofbegin = function (element, settings) { if (settings.container === undefined || settings.container === window) { var fold = $(window).scrollLeft(); } else { var fold = $(settings.container).offset().left; } return fold >= $(element).offset().left + settings.threshold + $(element).width(); }; /* Custom selectors for your convenience. */ /* Use as $("img:below-the-fold").something() */ $.extend($.expr[':'], { "below-the-fold": "$.belowthefold(a, {threshold : 0, container: window})", "above-the-fold": "!$.belowthefold(a, {threshold : 0, container: window})", "right-of-fold": "$.rightoffold(a, {threshold : 0, container: window})", "left-of-fold": "!$.rightoffold(a, {threshold : 0, container: window})" }); })(jQuery);