What is a navigation link called that has a placeholder in href?

Question

What is it called when a navigation link (<a href="#">) has a hash as placeholder without a landing page?

Answer 1

It's called a fragment URL or fragment identifier, although it's also known as just fragment, anchor or hashtag anchor

Answer 2

Take this URL:

www.example.com/foo.html#bar

The URL fragment of this URL is #bar. The main purpose it can serve is to link to particular part of the page, so that when the user opens this page, the browser will scroll to that part of the page automatically.

The link <a href="#">...</a> is linking to the current page with URL fragment set to empty. It's not really a placeholder URL, it does have an effect. If the current page URL displayed in the expanded address bar in the browser is http://example.com/#foobar , then clicking on the link <a href="#">...</a> will change the URL to http://example.com/# . It won't cause the page to reload, because only the URL fragment changed.

People use it as a placeholder URL, because setting the href to empty often doesn't have the desired effect.