程序实例代码如下所示：

using System;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.ComponentModel;

[assembly:TagPrefix("Beyondbit.App.Web.UI.WebControls", "BBit")]
namespace Beyondbit.App.Web.UI.WebControls
{

#region ElapsedEventArgs class
public class ElapsedEventArgs : EventArgs
{
    public int SignalTime;
}
#endregion

/// <summary>
/// 客户端定时器
/// </summary>
[DefaultProperty("Enabled"),
ToolboxData("<{0}:ClientTimer runat=server></{0}:ClientTimer>")]
public class ClientTimer : System.Web.UI.Control , System.Web.UI.IPostBackEventHandler // , System.Web.UI.IPostBackDataHandler
{
   public delegate void ElapsedEventHandler( object sender, ElapsedEventArgs e );
   public event ElapsedEventHandler Elapsed;

protected virtual void OnElapsed( ElapsedEventArgs e)
{
  if ( Elapsed != null )
  Elapsed(this, e);
}

private int signalTime = 0;

private int interval = 0 ;
[Description("设置或获取定时时间(毫秒)")]
public int Interval
{
  set
  {
    if( value <= 0 )
    throw new ArgumentException( "Interval时间间隔不能小于或等于0" );
     interval = value ;
   }
  get
  {
    return interval ;
   }
  }

private bool enabled = false ;
[Description("设置或获取定时器是否启用")]
public bool Enabled
{
  set{ enabled = value ; }
  get{ return enabled ; }
}

//public bool AutoReset = false ;

[Description("停止定时器")]
public void Stop()
{
   enabled = false ;
}

protected override void OnPreRender(EventArgs e)
{
   base.OnPreRender (e);

   if( this.enabled == false ) return;

   if( interval == 0 ) throw new ArgumentException( "定时器已启动，但Interval时间间隔没有设置" );

//js
string jsId = this.UniqueID + "_js";
string clientFunction = this.UniqueID + "_OnElapsed";

signalTime = signalTime + this.interval ;

string js = "<script language='javascript'>" +
"window.setTimeout( "+clientFunction+" , "+ this.signalTime +" );" +
"function " + clientFunction + "(){" +
Page.GetPostBackEventReference( this , "" + this.signalTime ) +
";}" +
"</script> ";

Page.RegisterStartupScript( jsId , js );

}

/// <summary>
/// 将此控件呈现给指定的输出参数。
/// </summary>
/// <param name="output"> 要写出到的 HTML 编写器 </param>
protected override void Render(HtmlTextWriter output)
{
//output.Write(Text);
}

#region IPostBackEventHandler 成员

public void RaisePostBackEvent( string eventArgument )
{
  if( eventArgument == "" ) throw new Exception( "eventArgument参数为空！" );
   signalTime = int.Parse( eventArgument ) ;

   ElapsedEventArgs e = new ElapsedEventArgs();
   e.SignalTime = signalTime ;

   this.OnElapsed( e );
}

#endregion

#region IPostBackDataHandler 成员

// public void RaisePostDataChangedEvent()
// {
// // TODO: 添加 ClientTimer.RaisePostDataChangedEvent 实现
// }
//
// public bool LoadPostData(string postDataKey, System.Collections.Specialized.NameValueCollection postCollection)
// {
// // TODO: 添加 ClientTimer.LoadPostData 实现
//
// string s = postCollection[ this.UniqueID + "_signalTime" ];
// if( s == null || s == "" ) return false;
//
// signalTime = Convert.ToInt32( s );
//
// return false;
// }

#endregion
}
}