An interesting approach to get the dirname of the current URL is to make use of your browser's built-in path resolution. You can do that by:
., i.e. the current directoryHTMLAnchorElement interface of the link to get the resolved URL or path equivalent to ..Here's one line of code that does just that:
Object.assign(document.createElement('a'), {href: '.'}).pathname
In contrast to some of the other solutions presented here, the result of this method will always have a trailing slash. E.g. running it on this page will yield /questions/3151436/, running it on https://stackoverflow.com/ will yield /.
It's also easy to get the full URL instead of the path. Just read the href property instead of pathname.
Finally, this approach should work in even the most ancient browsers if you don't use Object.assign:
function getCurrentDir () {
var link = document.createElement('a');
link.href = '.';
return link.pathname;
}