title: What does mongoose return when a find query is empty?
body: <p>I'm setting up a function that searches for a user based on an id and if no user is found, it creates a new one. I have no users yet so the query never returns a user. However, I'm unable to successfully check for this case. What exactly is returned when a <code>find</code> query is empty?</p>
  
  <pre><code> User.find(id,(error,user)=&gt;{
          if(error){
            console.log(error);
          }else{
            if(user == [] || user == null || user == undefined || user == {} || user == '[]'){
              User.addUser({"fbID":id,"lastMessage":"[]"},(error,response)=&gt;{
                if(error){
                  console.log(error);
                }else{
                  console.log(response);
                }
              });
            }else{
              console.log("User exists.");
            }
          }
        });
  </code></pre>