title: JS create objects with keys but no values
body: <p>When iterating with a for loop it's more convenient to use this:</p>
  
  <pre><code>for (var key in obj){ key }
  </code></pre>
  
  <p>than these:</p>
  
  <pre><code>for (var i in array){ var key = array[i]; key }
  for (var i = 0; i&lt; array.length;i++){ var key = array[i]; key }
  </code></pre>
  
  <p>But, obviously, declaring arrays is easier:</p>
  
  <pre><code>var array = ['key1', 'key2', 'key3']
  
  var obj =   { key1:'',key2:'',key3:'' }
  </code></pre>
  
  <p>Assuming I only care about keys and don't care about order, is there a way of declaring objects with just keys and no values (more easily than above)? I just don't like using</p>
  
  <pre><code>:'',    
  </code></pre>
  
  <p>It looks like a  weird smiley face.</p>
  
  <p>Edit:
  <code>for-of</code> would definitely be the way to go, just not yet.</p>