js检测cookie是否存在

function cookie(){ 
   var cookieArray=document.cookie.split("; ");
     var cookie=new Object(); 
     for (var i=0;i<cookieArray.length;i++){ 
      var arr=cookieArray[i].split("="); 
      if(arr[0]=='cookieID')return unescape(arr[1]); 
   }
   return "";
}