div 无缝滚动（内容超过就滚动，不超过不滚动）

<%@ Control Language="C#" AutoEventWireup="true" CodeFile="WebUserControl.ascx.cs" Inherits="WebUserControl" %>

<style type="text/css">
<!--
 #demo {
background: #FFF;
overflow:hidden;
height: 200px;
text-align: center;
float: left;

}

-->
</style>

<div id="demo">
<div id="demo1">

    <asp:SqlDataSource ID="SqlDataSource1" runat="server"
        ConnectionString="<%$ ConnectionStrings:WuLiuFaBuConnectionString %>"
        SelectCommand="SELECT top 10 * FROM [ZH_CarSource]"></asp:SqlDataSource>
    <asp:Repeater ID="Repeater1" runat="server" DataSourceID="SqlDataSource1">
   
    <ItemTemplate>
   
 
    <table style="width:100%; height:20px; border-bottom-style: dashed; border-bottom-width: 1px; border-bottom-color: #C0C0C0; line-height: 20px; ">
       <%--<a href="" >--%>
            <tr height="20px">
           
                <td width="30px">
                    <%# Eval("id") %>
                </td>
                <td width="70px">
                    <%# Eval("carplate") %></td>
                <td width="70px">
                    <%# Eval("cartype") %></td>
                 <td width="30px">
                     <%# Eval("carhigh") %></td>
                    <td width="30px">
                    <%# Eval("carlength") %></td>
                         <td width="30px">
                   <%# Eval("carweight") %></td>
                         <td width="50px">
                     <%# Eval("cardriver") %></td>
                         <td width="48px">
                    <%# Eval("carphone") %></td>
                   
                  <td width="50px"> <%# Eval("carrunstate") %> </td>
                  <td width="48px">  <%# Eval("carstate") %> </td>
                   <td width="48px">  <%# Eval("carroute") %> </td>
                 <td width="48px">  <%# Eval("driverid") %> </td>
                   
            </tr>
  
          <%-- </a>--%>
          </table>
     
    </ItemTemplate>
    </asp:Repeater>
</div>
<div id="demo2" ></div>
   
</div>
<script>
<!--
var speed=50; //数字越大速度越慢
var tab=document.getElementById("demo");
var tab1=document.getElementById("demo1");
var tab2=document.getElementById("demo2");

document.write(tab.clientHeight+"  "+tab1.clientHeight)

if(tab.clientHeight-tab2.offsetTop<=0) //通过tab的高度和tab2里tab顶部的高度来判断是否需要tab2有内容，如果tab2没有内容自然不用滚动
{
  tab2.innerHTML=tab1.innerHTML; //克隆demo1为demo2
  document.write("aaaaaaaaaaaaaaaaaaaaaaaa");
 
}

function Marquee(){
if(tab2.offsetTop-tab.scrollTop<=0)//当滚动至demo1与demo2交界时
 {tab.scrollTop-=tab1.offsetHeight} //demo跳到最顶端
else{ tab.scrollTop++  }

}
var MyMar=setInterval(Marquee,speed);
tab.onmouseover=function() {clearInterval(MyMar)};//鼠标移上时清除定时器达到滚动停止的目的
tab.onmouseout=function() {MyMar=setInterval(Marquee,speed)};//鼠标移开时重设定时器
-->
</script>