title: How to understand Object.hasOwnProperty("constructor")
body: <p>I'm a newer on JavaScript and have a question that confuses me a lot.</p>
  
  <p><code>Object.constructor</code> is a function, but <code>Object.hasOwnProperty("constructor") == false</code>.  Why? </p>
  
  <p>As we know the prev of Object is null, maybe <code>Object.prototype.__proto__ == null</code>. How add the "constructor"'s property of object? </p>