title: JQuery, cannot assign data attribute after creation
body: <p>I'm trying to add some data attributes to a list element after creation.</p>
  
  <pre><code>  var el = document.createElement('li');
    el.className = "list-group-item";
    el.attr({"data-content": contentForm, "data-type": contentType, "data-number": value});
  </code></pre>
  
  <p>The error is 'Uncaught TypeError: el.attr is not a function'</p>
  
  <p>I follow another discussion here, and I cannot find the issue...</p>