小米官网给我的感觉是大气、干净。很多特效的加入让人觉得耳目一新，big满满。 看到他们首页的轮播图实现挺有意思，于是自己模仿着写了一个。
大致的感觉出来了，贴个图先：
通过前端神器chrom的F12观察小米官网的html代码，不难看到他们使用5个div包裹图片并使用了定位通过z-index来控制div层级，通过控制每个div的opacity属性和display属性进行元素的显示、隐藏。
截图如下（红框内的opacity属性）：
好的，实现的手段知道了，那么页面布局先搞出来。
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/> <title>Mking_js_</title> <script type="text/javascript" src="https://www.jb51.net/js/moveopacity_1.js"></script> <style type="text/css"> #warp{ width:800px; height: 400px; margin: 20px auto; position: relative;} #imgWarp{ width:600px; height: 400px; position: absolute; top:0; left: 100px; display: inline-block; } .btn:hover{cursor: pointer;} .btn{line-height: 30px; text-align: center;font-size: 25px; font-weight: bold; color: #fff;width:80px; height: 30px;top:185px;background: #5f7c8a;position: absolute; border-radius: 3px; } .btn:nth-of-type(1){ left: 0; } .btn:nth-of-type(2) { right: 0; } img { position: absolute; width:600px; height: 400px; background-size:contain; opacity: 0; display: none; z-index: 0; } img:nth-of-type(1) { opacity: 1; display: block; z-index:5; } .links{ width:300px; height: 30px; position: absolute; right:100px; bottom: 10px; z-index: 10; } em{font-style: normal; display: inline-block; height: 30px; width: 30px; margin-right: 15px; border: 1px solid #000000; vertical-align: top; line-height: 30px; font-size: 20px; text-align: center;color: #fff; font-weight: bold; border-radius: 50%; background-color: #008000; border-color: #c0c0c0; box-sizing: border-box; } em.active{ background-color: #fff; color: #000000; } </style> </head> <body> <div> <div > <img src="https://www.jb51.net/product/1.jpg" TITLE="img1" /> <img src="https://www.jb51.net/product/2.jpg" TITLE="img2"/> <img src="https://www.jb51.net/product/3.jpg" TITLE="img3"/> <img src="https://www.jb51.net/product/4.jpg" TITLE="img4"/> <img src="https://www.jb51.net/product/5.jpg" TITLE="img5" /> </div> <span>left</span> <span>right</span> <div> <em></em> <em></em> <em></em> <em></em> <em></em> </div> </div> </body> </html>
结构已经有了下面就是添加js让它动起来。
页面中的js：
window.onload = function(){ var oLeft = document.getElementById("left"); var oRight = document.getElementById("right"); var oWarp = document.getElementById("imgWarp"); var aImg = oWarp.getElementsByTagName("img"); var aEm = document.getElementsByTagName("em"); var i = 5; btn = true; oLeft.onclick = function(){ clearInterval(autoTimer); if(btn){ btn=false; fnAutoLeft(); } }; function fnAutoLeft(){ var a = i % 5; i-=1; var b = i % 5; startOpacMove(aImg[a],0,aImg[b],100); setStyle(b); } oRight.onclick = function(){ if(btn){ //单位时间内只能触发一次元素的显示隐藏 clearInterval(autoTimer); btn=false; fnAutoRight(); } }; var count =0; function fnAutoRight(){ var a = i % 5; i+=1; var b = i % 5; startOpacMove(aImg[a],0,aImg[b],100); setStyle(b); if(i==10){ i=5; for(var j = 0;j<aImg.length;j++){ if(j==0){ aImg[0].style.cssText ="opacity: 1; z-index: 5; display: block;"; } else{ aImg[j].style.cssText ="opacity: 0; z-index: 0; display: none;"; } } } } var autoTimer = setInterval(fnAutoRight,5000); function setStyle(a){ for(var i=0;i<aEm.length;i++){ aEm[i].className=""; } aEm[a].className="active"; } }
运动的js：
function startOpacMove(obj1,tag1,obj2,tag2) { var iCur1 = 0; var iCur2 = 0; var iTimer = null; var iSpeed1 = -2; var iSpeed2 = 2; clearInterval(iTimer); iTimer = setInterval(function(){ var iBtn = true; iCur1 = css(obj1,'opacity')*100; iCur2 = css(obj2,'opacity')*100; iCur1 = Math.floor(iCur1); iCur2 = Math.floor(iCur2); if(iCur1 != tag1 && iCur2 != tag2){ iBtn = false; obj1.style.opacity = (iCur1+iSpeed1)/100; // console.log("隐藏元素时候的透明度值:"+(iCur1+iSpeed1)/100); obj1.style.filter = 'alpha(opacity='+(iCur1+iSpeed1)+')'; obj1.style.zIndex = 0; obj2.style.opacity = (iCur2+iSpeed2)/100; obj2.style.filter = 'alpha(opacity='+(iCur2+iSpeed2)+')'; obj2.style.zIndex = 5; obj2.style.display ="block"; } if(iBtn){ clearInterval(iTimer); obj1.style.display ="none"; obj1.style.opacity =0; obj2.style.opacity =1; btn = true; } },10); } function css(obj,attr){ if(obj.currentStyle){ //当前浏览器下存在currentStyle属性 return obj.currentStyle[attr]; }else{ return getComputedStyle(obj,false)[attr]; } }
看下js代码是如何让图画动起来的