[jQuery] How return value in jQuery ajax

[sam]

i have function
jQuery.ajax({
         type: "GET",
          url: url,
         data: queryString + '&btnSubmit=1',
      success: function(msg)
            {
              if(msg=0){

                if(msg)
                {
                     $("#errorid").val("");

                }
                else
                {
                    $("#email").val("");
                    document.getElementById("email").focus();
                }
              }
          }
      });
how to get msg in othe javascript function

function()
{
}
how can i use out of one function in other javascript function OR how
can i Stop one function from the other function