JavaScript JavaScript and the DOM Traversing the DOM Using parentNode to Traverse Up the DOM

Luke Markham
Luke Markham
Front End Web Development Techdegree Student 7,782 Points

Why does the tagName have to be capitalized?

 listDiv.addEventListener('click', (event) => {

if ( === 'BUTTON') {

 let li =;
  let ul = li.parentNode;




Why must "button" be capitalized to "BUTTON" ?

1 Answer

Steven Parker
Steven Parker
158,991 Points

You need to use upper case so you can match with the stored tag name you get from the system. As described on the MDN page (:point_left: use the link for more details):

For DOM trees which represent HTML documents, the returned tag name is always in the canonical upper-case form. For example, tagName called on a <div> element returns "DIV".