title: Is "type" a keyword in JavaScript?
body: <p>I just came across somebody using "type" in <a href="https://github.com/facebook/flux/blob/master/examples/flux-utils-todomvc/js/flux-infra/TodoActions.js" rel="noreferrer">a piece of ES6 code</a>. </p>
  
  <pre><code>export type Action =
    {
      type: 'todo/complete',
      id: string,
    } |
    {
      type: 'todo/create',
      text: string,
    } |
    {
      type: 'todo/destroy',
      id: string,
    } |
    {
      type: 'todo/destroy-completed',
    } |
    {
      type: 'todo/toggle-complete-all',
    } |
    {
      type: 'todo/undo-complete',
      id: string,
    } |
    {
      type: 'todo/update-text',
      id: string,
      text: string,
    };
  </code></pre>
  
  <p>Couldn't find anything that sheds light on it. Is it a keyword? What does it exactly do?</p>