title: hasAttribute vs hasOwnProperty
body: <p>I ran into some jquery code which attempts to use hasOwnProperty to access an html attribute.</p>
  
  <pre><code>&lt;input type="text" name="fname" placeholder="First name"&gt;
  
  &lt;script&gt;
      var e = $element.find('input')[0];
      if(!e.hasOwnProperty("placeholder")){...}
  &lt;/script&gt;
  </code></pre>
  
  <p>To my understanding, this should always be</p>
  
  <pre><code>if(!e.hasAttribute("placeholder")){...}
  </code></pre>
  
  <p>but what is the difference between hasAttribute and hasOwnProperty? <strong>Are they ever equivalent?</strong></p>