<script language="JavaScript">

NS4 = (document.layers) ? true : false;

function checkEnter(event,element)

{    

    var code = 0;

    if (NS4)

        code = event.which;

    else

        code = event.keyCode;

    if (code==13)

     {

         if(element.name=='tbUserName')//tbUserName-用户名文本框的Name

         {

              document.frmLogin.tbPassword.focus();//frmLogin-表单名称,tbPassword-密码文本杠框的Name

         }

         if(element.name=='tbPassword')

         {

              //document.frmLogin.submit();用这种方式提交,Asp.net页面会闪一下,但实际并未提交

              //用下面的代码才能提交,我是从asp.net生成的页面中查看源文件然后复制出来的

              if (typeof(Page_ClientValidate) != 'function' ||  Page_ClientValidate()) __doPostBack('lblLogin','');

         }

     }

}

</script>

tbUserName.Attributes.Add("onKeyPress","checkEnter(event,this)");

tbPassword.Attributes.Add("onKeyPress","checkEnter(event,this)");

System.IO.StreamReader sr=new System.IO.StreamReader(MapPath("Script")+"\\LoginScript.js");

this.RegisterClientScriptBlock("LoginScript",sr.ReadToEnd());

sr.Close();