url not being redirected to when starts with www

In my application I’ve got a method for redirecting to a url like so:

openURL() {
  window.open(this.url, '_blank').focus();
}

This will work fine if the URL starts with a http, so for example, if this.url is set to: https://www.example.com/...
this will work fine.

However if it does not have the https:// and just wwww.example.com/....., then what happens is that when it opens the new tab, the url becomes http://localhost:4200/...

I’m just not sure why the www is being replaced with http://localhost:4200/, what could be causing this?