title: Unable to search for user using parse.com query and javascript SDK
body: <p>Using parse.com and the JavaScript SDK, I want to create a query that checks if a user is already existing.</p>
  
  <p>There is example code here, which I've adopted and turned into the below code block. I'm getting an <code>Uncaught ReferenceError: username is not defined</code> error, which I don't understand why?</p>
  
  <p><a href="https://www.parse.com/docs/js_guide#users" rel="nofollow">https://www.parse.com/docs/js_guide#users</a></p>
  
  <pre><code>var friendFinder = Parse.Object.extend("_User");
  var query = new Parse.Query(Parse.User);
  query.equalTo(username, "d"); // find users that match
  query.find({
      success: function (friend) {
          if (friendName.length) {
              console.log("Success")
          }
      },
      error: function (error) {
          //Show if no user was found to match
  
  
      }
  });
  </code></pre>