jquery lazyload延迟加载图片
Lazy Load 是一个用 JavaScript 编写的 jQuery 插件. 它可以延迟加载长页面中的图片. 在浏览器可视区域外的图片不会被载入, 直到用户将页面滚动到它们所在的位置. 这与图片预加载的处理方式正好是相反的.
在包含很多大图片长页面中延迟加载图片可以加快页面加载速度. 浏览器将会在加载可见图片之后即进入就绪状态. 在某些情况下还可以帮助降低服务器负担.
LazyLoad.js
(function ($) { $.fn.lazyload = function (options) { var settings = { threshold: 0, failurelimit: 0, event: "scroll", effect: "show", 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; //我就把这里的一段代码删除了 /* 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);
html页面
<script src="@Url.Content("~/Scripts/jquery-1.4.4.min.js")" type="text/javascript"></script> <script src="/Scripts/lazyload.js" type="text/javascript"></script> <script type="text/javascript"> $(function () { $("img").lazyload(); }); </script> } <table align="center"> <tr>.... <th> 图片 </th>.... </tr> @foreach (System.Data.DataRow dr in Model.Rows) { <tr>.... <td> <img src="/Content/images/grey.gif" original="http://192.168.1.6:80/@(dr["fSKC"].ToString()).jpg" onerror="this.src='/Content/images/grey.gif';" /> </td>..... </tr> } </table> /*grey.gif为占位符 original为服务器加载图片的路径*/