JavaScript实现的轮播图

      当初学习JavaScript的时候，想学习轮播图是怎么写的，结果在百度搜了半天也很难搜出一个完整的轮播图案例。现在就分享一个用js写的轮播图供大家参考和学习，有什么错误的地方或有更好的方法也请大家提出来，共同讨论和进步。

　　下面是效果图。

     

　　

<div id="play">

<ol> 　　　　//按钮
<li class="active">1</li>
<li>2</li>
<li>3</li>
<li>4</li>
<li>5</li>
</ol>
<ul>
<li><a href="http:///"><img src="images/1.jpg" alt="广告一" /></a></li>
<li><a href="http:///"><img src="images/2.jpg" alt="广告二" /></a></li>
<li><a href="http:///"><img src="images/3.jpg" alt="广告三" /></a></li>
<li><a href="http:///"><img src="images/4.jpg" alt="广告四" /></a></li>
<li><a href="http://"><img src="images/5.jpg" alt="广告五" /></a></li>
</ul>

</div>

* { padding: 0; margin: 0; }
li { list-style: none; }
img { border: none; }

body { background: #ecfaff; }

#play { 470px; height: 150px; overflow: hidden; border: 1px solid #d8d8d8; margin: 100px auto 0; position: relative;}
.packet { 470px; height: 150px; position: relative; overflow:-hidden;}
ol { position: absolute; right: 5px; bottom: 5px; z-index: 2; }
ol li { float: left; margin-right: 3px; display: inline; cursor: pointer; background: #fcf2cf; border: 1px solid #f47500; padding: 2px 6px; color: #d94b01; font-family: arial; font-size: 12px;border-radius: 50%; }
.active { padding: 3px 8px; font-weight: bold; color: #ffffff; background: #ffb442; position: relative; bottom: 2px; }

ul { position: absolute; top: 0px; left: 0px; z-index: 1; background:white; 2350px; height: 150px; }
ul li { position:relative; 470px; height: 150px; top:0px; left:0px; float: left;}
ul img { float: left; 470px; height: 150px; }

下面是js

<script>

window.onload = function(){
var aLi = document.getElementsByTagName('ol')[0].getElementsByTagName('li');
var oUl = document.getElementsByTagName('ul')[0];
var aLi2 = oUl.getElementsByTagName('li');
var iNow = 0;
var iNow2 = 0;
var timer = null;

for(var i=0;i<aLi.length;i++){
aLi[i].index = i;
aLi[i].onmouseover = function(){
for(var i=0;i<aLi.length;i++){
aLi[i].className = '';
};
this.className = 'active';

startMove(oUl,{'left' : -470*this.index});  　　//startMove是封装的一个基于时间的运动框架，在文章最后有展示源码，有兴趣的可以看一看
iNow = this.index;
iNow2 = this.index;
clearInterval(timer);
};

aLi[i].onmouseout = function(){
timer = setInterval(toRun,2000);
};
}

timer = setInterval(toRun,2000);

function toRun(){
if(iNow==aLi.length-1){
iNow = 0;
aLi2[0].style.position = 'relative';
aLi2[0].style.left = 470 * aLi2.length + 'px';
}
else{
iNow++;
}

iNow2++;

for(var i=0;i<aLi.length;i++){
aLi[i].className = '';
};
aLi[iNow].className = 'active';
startMove(oUl,{ left : -470 * iNow2},function(){

clearInterval(timer);
timer = setInterval(toRun,2000);

if(iNow==0){
aLi2[0].style.position = 'static';
oUl.style.left = 0;
iNow2 = 0;
}

});
}

};

</script>

startMove源码

function startMove(obj,json,times,fx,fn){ //obj:对象 json：目的 times：时间 fx：方式，例如linear fn：回调函数

if( typeof times == 'undefined' ){
times = 400;
fx = 'linear';
}

if( typeof times == 'string' ){
if(typeof fx == 'function'){
fn = fx;
}
fx = times;
times = 400;
}
else if(typeof times == 'function'){
fn = times;
times = 400;
fx = 'linear';
}
else if(typeof times == 'number'){
if(typeof fx == 'function'){
fn = fx;
fx = 'linear';
}
else if(typeof fx == 'undefined'){
fx = 'linear';
}
}

var iCur = {};

for(var attr in json){
iCur[attr] = 0;

if( attr == 'opacity' ){
iCur[attr] = Math.round(getStyle(obj,attr)*100);
}
else{
iCur[attr] = parseInt(getStyle(obj,attr));
}

}

var startTime = now();

clearInterval(obj.timer);

obj.timer = setInterval(function(){

var changeTime = now();

var t = times - Math.max(0,startTime - changeTime + times); //0到2000

for(var attr in json){

var value = Tween[fx](t,iCur[attr],json[attr]-iCur[attr],times);

if(attr == 'opacity'){
obj.style.opacity = value/100;
obj.style.filter = 'alpha(opacity='+value+')';
}
else{
obj.style[attr] = value + 'px';
}

}

if(t == times){
clearInterval(obj.timer);
if(fn){
fn.call(obj);
}
}

},13);

function getStyle(obj,attr){
if(obj.currentStyle){
return obj.currentStyle[attr];
}
else{
return getComputedStyle(obj,false)[attr];
}
}

function now(){
return (new Date()).getTime();
}

}

var Tween = {
linear: function (t, b, c, d){ //匀速
return c*t/d + b;
},
easeIn: function(t, b, c, d){ //加速曲线
return c*(t/=d)*t + b;
},
easeOut: function(t, b, c, d){ //减速曲线
return -c *(t/=d)*(t-2) + b;
},
easeBoth: function(t, b, c, d){ //加速减速曲线
if ((t/=d/2) < 1) {
return c/2*t*t + b;
}
return -c/2 * ((--t)*(t-2) - 1) + b;
},
easeInStrong: function(t, b, c, d){ //加加速曲线
return c*(t/=d)*t*t*t + b;
},
easeOutStrong: function(t, b, c, d){ //减减速曲线
return -c * ((t=t/d-1)*t*t*t - 1) + b;
},
easeBothStrong: function(t, b, c, d){ //加加速减减速曲线
if ((t/=d/2) < 1) {
return c/2*t*t*t*t + b;
}
return -c/2 * ((t-=2)*t*t*t - 2) + b;
},
elasticIn: function(t, b, c, d, a, p){ //正弦衰减曲线（弹动渐入）
if (t === 0) {
return b;
}
if ( (t /= d) == 1 ) {
return b+c;
}
if (!p) {
p=d*0.3;
}
if (!a || a < Math.abs(c)) {
a = c;
var s = p/4;
} else {
var s = p/(2*Math.PI) * Math.asin (c/a);
}
return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
},
elasticOut: function(t, b, c, d, a, p){ //正弦增强曲线（弹动渐出）
if (t === 0) {
return b;
}
if ( (t /= d) == 1 ) {
return b+c;
}
if (!p) {
p=d*0.3;
}
if (!a || a < Math.abs(c)) {
a = c;
var s = p / 4;
} else {
var s = p/(2*Math.PI) * Math.asin (c/a);
}
return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
},
elasticBoth: function(t, b, c, d, a, p){
if (t === 0) {
return b;
}
if ( (t /= d/2) == 2 ) {
return b+c;
}
if (!p) {
p = d*(0.3*1.5);
}
if ( !a || a < Math.abs(c) ) {
a = c;
var s = p/4;
}
else {
var s = p/(2*Math.PI) * Math.asin (c/a);
}
if (t < 1) {
return - 0.5*(a*Math.pow(2,10*(t-=1)) *
Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;
}
return a*Math.pow(2,-10*(t-=1)) *
Math.sin( (t*d-s)*(2*Math.PI)/p )*0.5 + c + b;
},
backIn: function(t, b, c, d, s){ //回退加速（回退渐入）
if (typeof s == 'undefined') {
s = 1.70158;
}
return c*(t/=d)*t*((s+1)*t - s) + b;
},
backOut: function(t, b, c, d, s){
if (typeof s == 'undefined') {
s = 3.70158; //回缩的距离
}
return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;
},
backBoth: function(t, b, c, d, s){
if (typeof s == 'undefined') {
s = 1.70158;
}
if ((t /= d/2 ) < 1) {
return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;
}
return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;
},
bounceIn: function(t, b, c, d){ //弹球减振（弹球渐出）
return c - Tween['bounceOut'](d-t, 0, c, d) + b;
},
bounceOut: function(t, b, c, d){
if ((t/=d) < (1/2.75)) {
return c*(7.5625*t*t) + b;
} else if (t < (2/2.75)) {
return c*(7.5625*(t-=(1.5/2.75))*t + 0.75) + b;
} else if (t < (2.5/2.75)) {
return c*(7.5625*(t-=(2.25/2.75))*t + 0.9375) + b;
}
return c*(7.5625*(t-=(2.625/2.75))*t + 0.984375) + b;
},
bounceBoth: function(t, b, c, d){
if (t < d/2) {
return Tween['bounceIn'](t*2, 0, c, d) * 0.5 + b;
}
return Tween['bounceOut'](t*2-d, 0, c, d) * 0.5 + c*0.5 + b;
}
}