title: Combine objects in node.js
body: <p>My node.js app receives two json objects from external API. The first object is weather data by days where the keys are unix timestamp:</p>
  
  <pre><code>{
    1491368400: /*some data*/,
    1491454800: /*some data*/,
    1491541200: /*some data*/,
  }
  </code></pre>
  
  <p>The second object is weather by hours for these days (if there are three days in object above, there are 3 * 24 keys in this object):</p>
  
  <pre><code>{
    1491368400: /*some data*/,
    1491372000: /*some data*/,
    1491375600: /*some data*/,
    .............................
    /* there are 72 keys, 24 for every proper day from object above */
  }
  </code></pre>
  
  <p>I need to combine these two objects: take data from second object with hours and calculate average values for each day from first object and put these values into the first object.
  I think it would be good to do it with Transform Stream, but have no idea how to do it properly. I need just a schema how to do it, not detailed solution.</p>
  
  <p><strong>UPDATE</strong></p>
  
  <p>The main thing I want to know is how to merge two objects without putting much pressure on event loop.</p>