延时加载图片的js代码
- 作者:网页模板
- 大小:0.15MB
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- 发布时间:2014-05-12 09:47
特效介绍
延时加载图片的js代码:在做图片网站时,往往会出现,整个页面的图片同时在缓慢加载,非常不美观。本插件的作用顾名思义,先让需要显示图片的位置先加载一张小图片,等到大图完全加载完成之后再显示出来。由于本插件的图片比较小,加载可能比较快,看不出效果。在预览本插件时,请按ctrl+F5多次查看。还有,本图片延时加载插件下载到本地是没有效果的,因为图片也在本地,加载太快,看不出来。使用方法
1、CSS样式:<style type="text/css"> body,div,ul,li{margin:0;padding:0;} #box{width:770px;margin:0 auto;padding:10px 0 0 10px;background:#f00;overflow:hidden;zoom:1;} #box li{float:left;width:375px;height:225px;color:#fff;padding:10px 0;display:inline;text-align:center;margin:0 10px 10px 0;background:#000 url(images/loading.gif) 50% 50% no-repeat;} #box li img.loaded{height:225px;vertical-align:middle;} </style>2、JS代码:
<script type="text/javascript"> var fgm = { on: function(element, type, handler) { return element.addEventListener ? element.addEventListener(type, handler, false) : element.attachEvent("on" + type, handler) }, bind: function(object, handler) { return function() { return handler.apply(object, arguments) } }, pageX: function(element) { return element.offsetLeft + (element.offsetParent ? arguments.callee(element.offsetParent) : 0) }, pageY: function(element) { return element.offsetTop + (element.offsetParent ? arguments.callee(element.offsetParent) : 0) }, hasClass: function(element, className) { return new RegExp("(^|\\s)" + className + "(\\s|$)").test(element.className) }, attr: function(element, attr, value) { if(arguments.length == 2) { return element.attributes[attr] ? element.attributes[attr].nodeValue : undefined } else if(arguments.length == 3) { element.setAttribute(attr, value) } } }; //延时加载 function LazyLoad(obj) { this.lazy = typeof obj === "string" ? document.getElementById(obj) : obj; this.aImg = this.lazy.getElementsByTagName("img"); this.fnLoad = fgm.bind(this, this.load); this.load(); fgm.on(window, "scroll", this.fnLoad); fgm.on(window, "resize", this.fnLoad); } LazyLoad.prototype = { load: function() { var iScrollTop = document.documentElement.scrollTop || document.body.scrollTop; var iClientHeight = document.documentElement.clientHeight + iScrollTop; var i = 0; var aParent = []; var oParent = null; var iTop = 0; var iBottom = 0; var aNotLoaded = this.loaded(0); if(this.loaded(1).length != this.aImg.length) { for(i = 0; i < aNotLoaded.length; i++) { oParent = aNotLoaded[i].parentElement || aNotLoaded[i].parentNode; iTop = fgm.pageY(oParent); iBottom = iTop + oParent.offsetHeight; if((iTop > iScrollTop && iTop < iClientHeight) || (iBottom > iScrollTop && iBottom < iClientHeight)) { aNotLoaded[i].src = fgm.attr(aNotLoaded[i], "data-img") || aNotLoaded[i].src; aNotLoaded[i].className = "loaded"; } } } }, loaded: function(status) { var array = []; var i = 0; for(i = 0; i < this.aImg.length; i++) eval("fgm.hasClass(this.aImg[i], \"loaded\")" + (!!status ? "&&" : "||") + "array.push(this.aImg[i])"); return array } }; //应用 fgm.on(window, "load", function () {new LazyLoad("box")}); </script>3、html代码:
<ul id="box"> <li><img src="img/none.gif" data-img="images/1.jpg" /></li> <li><img src="img/none.gif" data-img="images/2.jpg" /></li> <li><img src="img/none.gif" data-img="images/3.jpg" /></li> <li><img src="img/none.gif" data-img="images/4.jpg" /></li> <li><img src="img/none.gif" data-img="images/5.jpg" /></li> <li><img src="img/none.gif" data-img="images/6.jpg" /></li> </ul>
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