title: Updating a shared property between objects
body: <p>I have two objects that share a property <code>foo</code>.</p>
  
  <pre><code>let obj = {
    // ...
    foo: "ba",
    // ...
  };
  let obj2 = {
    // ...
    foo: obj.foo,
    // ...
  }
  </code></pre>
  
  <p>Is there a way that by updating <code>obj.foo</code> or <code>obj2.foo</code> the other one would have the same value as the updated one? For example</p>
  
  <pre><code>obj.foo += "r"
  console.log(obj2.foo); // "bar"
  </code></pre>