焦点轮播图

*{ margin: 0; padding: 0; text-decoration: none;}

body { padding: 20px;}

#container { width: 600px; height: 400px; border: 3px solid #333; overflow: hidden; position: relative;}

#list { width: 4200px; height: 400px; position: absolute; z-index: 1;}

#list img { float: left;}

#buttons { position: absolute; height: 10px; width: 100px; z-index: 2; bottom: 20px; left: 250px;}

#buttons span { cursor: pointer; float: left; border: 1px solid #fff; width: 10px; height: 10px; border-radius: 50%; background: #333; margin-right: 5px;}

#buttons .on {  background: orangered;}

.arrow { cursor: pointer; display: none; line-height: 39px; text-align: center; font-size: 36px; font-weight: bold; width: 40px; height: 40px;  position: absolute; z-index: 2; top: 180px; background-color: RGBA(0,0,0,.3); color: #fff;}

.arrow:hover { background-color: RGBA(0,0,0,.7);}

#container:hover .arrow { display: block;}

#prev { left: 20px;}

#next { right: 20px;}

window.onload = function () {

var container = document.getElementById('container');

var list = document.getElementById('list');

var buttons = document.getElementById('buttons').getElementsByTagName('span');

var prev = document.getElementById('prev');

var next = document.getElementById('next');

var index = 1;

var len = 5;

var animated = false;

var interval = 3000;

var timer;

function animate (offset) {

if (offset == 0) {

return;

}

animated = true;

var time = 300;

var inteval = 10;

var speed = offset/(time/inteval);

var left = parseInt(list.style.left) + offset;

var go = function (){

if ( (speed > 0 && parseInt(list.style.left) < left) || (speed < 0 && parseInt(list.style.left) > left)) {

list.style.left = parseInt(list.style.left) + speed + 'px';

setTimeout(go, inteval);

}

else {

list.style.left = left + 'px';

if(left>-200){

list.style.left = -600 * len + 'px';

}

if(left

list.style.left = '-600px';

}

animated = false;

}

}

go();

}

function showButton() {

for (var i = 0; i < buttons.length ; i++) {

if( buttons[i].className == 'on'){

buttons[i].className = '';

break;

}

}

buttons[index - 1].className = 'on';

}

function play() {

timer = setTimeout(function () {

next.onclick();

play();

}, interval);

}

function stop() {

clearTimeout(timer);

}

next.onclick = function () {

if (animated) {

return;

}

if (index == 5) {

index = 1;

}

else {

index += 1;

}

animate(-600);

showButton();

}

prev.onclick = function () {

if (animated) {

return;

}

if (index == 1) {

index = 5;

}

else {

index -= 1;

}

animate(600);

showButton();

}

for (var i = 0; i < buttons.length; i++) {

buttons[i].onclick = function () {

if (animated) {

return;

}

if(this.className == 'on') {

return;

}

var myIndex = parseInt(this.getAttribute('index'));

var offset = -600 * (myIndex - index);

animate(offset);

index = myIndex;

showButton();

}

}

container.onmouseover = stop;

container.onmouseout = play;

play();

}