title: Get values for a subset of keys
body: <p>I'm caching some data in a <code>Map</code> by Id. And in an additional array a store the Ids of all changed objects.</p>
  
  <p>Is there a way to get all changed values from my chache?</p>
  
  <pre><code>var cache = {id1 : {a:1, b:2},
               id2 : {a:5, b:2},
               id3 : {a:1, b:4}};
  
  var changed = ["id1", "id3"];
  </code></pre>
  
  <p>Right now I solve it like this, but I bet there is a smarter solution in JS.</p>
  
  <pre><code>var result = [];
  for(var id of changed) {
      result.push(cache[id]);
  }
  </code></pre>