title: node.js mongodb find() results to array but not use .filter
body: <p>I trying to use <code>Array.filter()</code> on result returned from <code>mongodb.find()</code>, 
  but it's not working!<br/> I am getting this error:</p>
  
  <blockquote>
    <p>(TS) Property 'filter' does not exist on type '{}'.</p>
  </blockquote>
  
  <pre><code>function find(collectionName: string, filter: any = {},callback: Function) {
      const MongoClient = require('mongodb').MongoClient;
      let url = "mongodb://localhost:27017/test";
  
      MongoClient.connect(url, function (err, db) {
          if (err) {
              callback(err, null);
              //throw err;
              db.close();
          } else {
              let rs = db.collection(collectionName).find(filter, { _id: false });
  
             rs.toArray(function (err, result) {
                  if (err) throw err;
                  callback(null,  result);
                  db.close();
              });               
  
          }
  
      });//MongoClient
  
  }
  </code></pre>