<!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <title>原生Js页面滚动延迟加载图片</title> <style type="text/css"> * { margin:0; padding:0 } img.scrollLoading { border:1px solid #ccc; display:block; margin-top:10px; } </style> </head> <body> <div></div> </body> </html> <script type="text/javascript"> var _CalF = { $:function(object){//选择器 if(object === undefined ) return; var getArr = function(name,tagName,attr){ var tagName = tagName || '*', eles = document.getElementsByTagName(tagName), clas = (typeof document.body.style.maxHeight === "undefined") ? "className" : "class";//ie6 attr = attr || clas, Arr = []; for(var i=0;i<eles.length;i++){ if(eles[i].getAttribute(attr)==name){ Arr.push(eles[i]); } } return Arr; }; if(object.indexOf('#') === 0){ //#id return document.getElementById(object.substring(1)); } else if(object.indexOf('.') === 0){ //.class return getArr(object.substring(1)); } else if(object.match(/=https://www.jb51.net/g)){ //attr=name return getArr(object.substring(object.search(/=https://www.jb51.net/g)+1),null,object.substring(0,object.search(/=https://www.jb51.net/g))); } else if(object.match(/./g)){ //tagName.className return getArr(object.split('.')[1],object.split('.')[0]); } }, getPosition : function(obj) { //获取元素在页面里的位置和宽高 var top = 0, left = 0, width = obj.offsetWidth, height = obj.offsetHeight; while(obj.offsetParent){ top += obj.offsetTop; left += obj.offsetLeft; obj = obj.offsetParent; } return {"top":top,"left":left,"width":width,"height":height}; } }; //添加图片list var _temp = []; for (var i = 1; i < 21; i ++) { _temp.push('<img data-src="http://images.cnblogs.com/cnblogs_com/Darren_code/311197/o_' + i + '.jpg" src="https://images.cnitblog.com/blog/150659/201306/23160223-c81dd9aa9a2a4071a47b0ced2c9118bc.gif" /><br />图片' + i); } _CalF.$("#content").innerHTML = _temp.join(""); function scrollLoad(){ this.init.apply(this, arguments); } scrollLoad.prototype ={ init : function(className){ var className = "img."+className, imgs = _CalF.$(className), that = this; this.imgs = imgs; that.loadImg(); window.onscroll = function(){ that.time = setTimeout(function(){ that.loadImg(); },400); } }, loadImg : function(){ var imgs = this.imgs.reverse(), //获取数组翻转 len = imgs.length; if(imgs.length===0){ clearTimeout(this.time); return; } for(var j=len-1;j>=0;j--){ //递减 var img = imgs[j], imgTop = _CalF.getPosition(img).top, imgSrc = img.getAttribute("data-src"), offsetPage = window.pageYOffset ? window.pageYOffset : window.document.documentElement.scrollTop,//滚动条的top值 bodyHeight = document.documentElement.clientHeight; //body的高度 if((offsetPage+bodyHeight/2) > (imgTop-bodyHeight/2)){ img.src = imgSrc; this.imgs.splice(j,1); } } } } var img1 = new scrollLoad("scrollLoading"); </script>
原生js页面滚动延迟加载图片
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