javascript里判断用户是否刷新了网页。并在用户刷新网页的时候提示用户，或是禁止

<SCRIPT>
if(GetCookie("x") != null )
{
 alert("不要刷新");
}
 

SetCookie("x","x"
)
function SetCookie(sName, sValue)
{
  document.cookie = sName + "=" + escape(sValue) + ";";
}

function GetCookie(sName)
{
  var aCookie = document.cookie.split("; ");
  for (var i=0; i < aCookie.length; i++)
  {   
    var aCrumb = aCookie[i].split("=");
    if (sName == aCrumb[0])
      return unescape(aCrumb[1]);
  }
  return null;
}
</SCRIPT>