Jquery global variable?

Jquery global variable?

Hello everxbody i have a big problem....

i want to read a inputfiel (land) and send this to my autocomplete file ... but this is not working there is always undefine... so how can i make this variable global that this is working? thank you very much

$("#land").change(function(){
   $.myvariable = $("#land").val();
   return $.myvariable;
});

   $("#plz").autocomplete("searchplz.php?land="+$.myvariable,{
      minChars: 1,
      width: 200,
      autoFill: false,
      mustMatch: true,
      formatItem: function(data) {
         return data[0] +" "+ data[1];
      },
      formatResult: function(data) {
         return data[0];
      }
   });