title: Why does this points to an empty object in the following js code?
body: <p>I have thought this would points to the object person but it actually points to an empty object. Can anyone explain? </p>
  
  <pre><code>var person = {
      name: 'James',
      birthYear: '1991',
      getAge: () =&gt; new Date().getFullYear() - this.birthYear // this points to an empty object here. test in nodejs.
  }
  </code></pre>