天猫轮播图
在做网页的时候，轮播图很常见，今天我们就做一种轮播图，通过轮播图来熟悉JavaScript的操作。
样式如下所示：
执行代码如下所示：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<style type="text/css">
*{
margin: 0;
padding: 0;
}
.box{
800px;
height: 300px;
position: relative;
overflow: hidden;
margin: 100px auto;
}
.box .slider{
100%;
height: 100%;
}
.box .slider ul{
1000%;
list-style: none;
position: absolute;
top: 0;
left: 0;
}
.box .slider img{
vertical-align: top;
}
.box .slider ul li{
float: left;
}
.box .scroll_nav{
list-style: none;
position: absolute;
right: 20px;
bottom: 10px;
}
.box .scroll_nav li{
float: left;
20px;
height: 20px;
background-color: #000;
color: #fff;
text-align: center;
font-size: 12px;
font-family: "微软雅黑";
line-height: 20px;
cursor: pointer;
border-radius: 50%;
margin-right: 5px;
}
.box .scroll_nav li.current{
background-color: #356acb;
}
.box .arr{
40px;
height: 50px;
font-size: 35px;
font-family: "黑体";
line-height: 50px;
background-color: rgba(0,0,0,0.3); /*这种方式能让背景透明而文本不收影响*/
color: #fff;
text-align: center;
position: absolute;
top: 125px;
font-weight: bold;
display: none;
cursor: pointer;
/* opacity: 0.1; opacity属性会让盒子半透明，与此同时它也会让黑子内部的文本半透明*/
}
.box .arr_prev{
left: 5px;
}
.box .arr_next{
right: 5px;
}
</style>
</head>
<body>
<div class="box" id="scroll">
<div class="slider" id="sl">
<ul id="sl_ul">
<li><img src="imgs/1.jpg" alt=""></li>
<li><img src="imgs/2.jpg" alt=""></li>
<li><img src="imgs/3.jpg" alt=""></li>
<li><img src="imgs/4.jpg" alt=""></li>
<li><img src="imgs/5.jpg" alt=""></li>
</ul>
</div>
<ul class="scroll_nav" id="sc_nav">
</ul>
<span class="arr arr_prev" id="prev">></span>
<span class="arr arr_next" id="next">></span>
</div>
</body>
</html>
javascript代码部分如下所示：
function $(id){
return document.getElementById(id);
}
//1、实现左右箭头的显示与隐藏
sName = '';window.onload = function(){
$('scroll').onmouseover = function(){
var arrs = $('scroll').getElementsByClassName('arr');
for (var i = 0; i < arrs.length; i++) {
arrs[i].style.display = 'block';
}
}
$('scroll').onmouseout = function(){
var arrs = $('scroll').getElementsByClassName('arr');
for (var i = 0; i < arrs.length; i++) {
arrs[i].style.display = 'none';
}
}
//2、实现轮播导航条
//2.2动态生成导航条内容
var imgCount = $('sl_ul').getElementsByTagName('li').length;
//2.2
for (var i = 0; i < imgCount; i++) {
var li = document.createElement('li');
li.innerHTML = i+1;
if(i == 0){
li.className = "current";
}
li.setAttribute('index',i);
li.onclick = function(){
var lis = $('sc_nav').getElementsByTagName('li');
for (var i = 0; i < lis.length; i++) {
lis[i].clas
}
this.className = 'current';
var index = parseInt(this.getAttribute('index'));
target = index * -800;
}
$('sc_nav').appendChild(li);
}
//
var leader = 0;
var target = 0;
setInterval(function(){
leader = leader + (target-leader)/10;
$('sl_ul').style.left = leader + 'px';
}, 10)
// 实现左右箭头点击
$('next').onclick = function(){
if(target > -3200){
target -= 800;
}else{
target = 0;
}
setCurrent();
}
$('prev').onclick = function(){
if(target<0){
target += 800;
}
setCurrent();
}
// 导航度对选中的LI，与左右箭头切换图片后，相照应
function setCurrent(){
var index = Math.abs(target/800);
var lis = $('sc_nav').getElementsByTagName('li');
for (var i = 0; i < lis.length; i++) {
lis[i].className = '';
}
lis[index].className = 'current';
}
}
// 2.3.1点击导航项，做动画效果
// 2.3排他思想完成点击导航项的样式