title: What is the difference between object keys with quotes and without quotes?
body: <p>Is there any difference between</p>
  
  <pre><code>obj = {'foo': 'bar'} 
  </code></pre>
  
  <p>and</p>
  
  <pre><code>obj = {foo: 'bar'}
  </code></pre>
  
  <p>I have noticed that you can't use <code>-</code> in the key when I don't use the quotes. But does it actually make a difference? If yes, which?</p>