title: Storing arrays in ES6 Set and accessing them by value
body: <p>Is there a simple way to verify that an ES6 Set contains a value that is a particular array? I'd like a solution that doesn't require me to use a reference:</p>
  
  <pre><code>var set = new Set();
  
  var array = [1, 2];
  set.add(array);
  set.has(array); // true
  
  set.add([3, 4]);
  set.has([3, 4]); // false
  </code></pre>
  
  <p>So far my solution is to store everything as a string, but this is annoying:</p>
  
  <pre><code>set.add([3, 4].toString());
  set.has([3, 4].toString()); // true
  </code></pre>