title: Node.js - wait for multiple async calls
body: <p>I'm trying to make multiple MongoDB queries before I render a Jade template, but I can't quite figure out how to wait until all the Mongo Queries are completed before rendering the template. </p>
  
  <pre><code>exports.init = function(req, res){
  
  
      var NYLakes = {};
      var NJLakes = {};
      var filterNY = {"State" : "NY"};
      db.collection('lakes').find(filterNY).toArray(function(err, result) {
          if (err) throw err;
          NYLakes = result;
      });
  
      var filterNJ = {"State" : "NJ"};
      db.collection('lakes').find(filterNJ).toArray(function(err, result) {
          if (err) throw err;
          NJLakes = result;
      });
  
      res.render('explore/index', {
              NYlakes: NYLakes,
              NJlakes: NJLakes
      });
  
  };
  </code></pre>