title: Chaining .then() calls in ES6 promises
body: <p>I thought it was supposed to be possible to chain the .then() method when using ES6 Promises. In other words I thought that when a promise is resolved the value passed to the resolve function should be passed to any chained <em>then</em> handlers. If this is so how come <em>value</em> comes back undefined in the chained <em>then</em> handler below?</p>
  
  <pre><code>function createPromise() {
    return new Promise((resolve) =&gt; {
      resolve(true);
    });
  }
  
  createPromise()
    .then((value) =&gt; {
      console.log(value); // expected: true, actual: true
    })
    .then((value) =&gt; {
      console.log(value); // expected: true, actual: undefined
    });
  </code></pre>