Magento加速利器——lazyload

Magento的速度是令人头疼的问题，我现在介绍一种前端的加速方法。说到lazyload,相信很多人都不陌生，现在很多网站都已经用到这个技术，他可以延迟加载长页面的图片。对于Magento这样的商城网站的加速就很明显了。我今天说的这个lazyload是经过POPO改造的（强逼我给他加外连……）。下面我放一些测试的数据，我正在做的一个网站的列表页。

很明显的就能看出差距。接下来写下用法：

首先加上jQuery,lazyload两段js。

lazyload：

(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; /* When appear is triggered load original image. */ $(self).one("appear", function() { if (!this.loaded) { $("<img alt="" />") .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})" }); $(function(){ $("img[original]").lazyload({ threshold : 200,effect: "fadeIn" }); }); })(jQuery); 

然后修改图片的路径

例如：<img alt=”" src=”<?php echo $this->getSkinUrl(‘images/co.jpg’) ?>”/>

修改为<img  alt=”"  original=”<?php echo $this->getSkinUrl(‘images/co.jpg’) ?>” src=”……”/>。

后面这个src里的图片是一个1像素的透明gif图片。

这样就可以了，有兴趣的可以尝试下。