JS Variable looses result Outside Function brackets

Question

data variable, looses results, outside the find function brackets.

     var data = null;
     function search(file) {
    find(file, function(err, results) {
      if(err) {
        return console.error(err);
      }
      //console.dir(results);
          data = results;
    });
    //data looses results;
      }

function results_copy(results) {
    data = results;
    return data;
}