title: why this pointing to global object
body: <p>Here why <strong>this</strong> pointing to global object(window).<br/>
  I know that using arrow function or closure or call/apply/bind, I can make it point to person object.<br/>
  But I am not at all clear that why <strong>this</strong> pointing to global object(window).</p>
  <pre><code>var person={
    name:'xyz',
    printName: function() {
      function displayName() {
          console.log(this);
      }
      displayName();
    }
  }
  person.printName();
  </code></pre>