<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>slider</title>
<style>
*{
  padding: 0;
  margin: 0;
}
li{
  list-style-type: none;
}
body{
  margin: 50px;
}
.wrap{
  border: 3px solid #f00;
  width: 600px;
  height: 200px;
  position: relative;
  overflow: hidden;
}
.wrap ul{
  overflow: hidden;
  position:absolute;
  width: 1600px;
  left: 0;
  top: 0;
  _height:1px;
}
.wrap ul li{
  float: left;
  width: 200px;
}
</style>
</head>
<body>
<a href="javascript:;" class="goLeft">向左走</a>
<a href="javascript:;" class="goRight">向右走</a>
<div class="wrap">
  <ul>
    <li><img src="1.jpg" alt=""></li>
    <li><img src="2.jpg" alt=""></li>
    <li><img src="3.jpg" alt=""></li>
    <li><img src="4.jpg" alt=""></li>
    <li><img src="5.jpg" alt=""></li>
  </ul>
</div>
<script src="jquery-1.7.2.min.js"></script>
<script src="slider.js"></script>
</body>
</html>

slider.js

// 如果想要使一個元素運動起來，一般情況下這個元素須要具有position屬性absolute/relative
$(function(){
  var oul = $('.wrap ul');
  var oulHtml = oul.html();
  oul.html(oulHtml+oulHtml)
  var timeId = null;
  var ali = $('.wrap ul li');
  var aliWidth = ali.eq(0).width();
  var aliSize = ali.size();
  var ulWidth = aliWidth*aliSize;
  oul.width(ulWidth); //1600px
  var speed = 2;
  function slider(){
    if(speed<0){
      if(oul.css('left')==-ulWidth/2+'px'){
      oul.css('left',0);
      }
      oul.css('left','+=-2px');
    }
    if(speed>0){
      if(oul.css('left')=='0px'){
      oul.css('left',-ulWidth/2+'px');
      }
      oul.css('left','+='+speed+'px');
    }
   }
  // setInterval()函數(shù)的作用是：每隔一段時間，執(zhí)行該函數(shù)里的代碼
   timeId = setInterval(slider,30);
  $('.wrap').mouseover(function(){
    // clearInterval()函數(shù)的作用是用來清除定時器
    clearInterval(timeId);
  });
  $('.wrap').mouseout(function(){
    timeId = setInterval(slider,30);
  });
  $('.goLeft').click(function(){
    speed=-2;
  });
  $('.goRight').click(function(){
    speed=2;
  });
});

效果圖如下：