title: Object property overwrites
body: <p>Doing a tutorial...came across:</p>
  
  <pre><code>let user1 = { name: 'Bob' };
  let user2 = { name: 'Ross' };
  let total = {};
  total[user1] = 5;
  total[user2] = 42;
  </code></pre>
  
  <p>Why does total user1 get overwritten to 42?  I imagine this all looking like this now:</p>
  
  <p>total = {{ user1 = { name: 'Bob' } : 5}, { user2 = { name: 'Ross' } : 42 };</p>
  
  <p>So total contains two object properties which map to value 5 and 42?  How do you access the name properties in total[user1] and total[user2]?  Also, why does 42 overwrite the 5?  I can't see exactly what's happening.</p>