Created by: MartijnCuppens
The prev() function doesn't take nodes other than elements into account. Also we could simplify things a lot using the previousElementSibling property. This property isn't fully supported in IE, it only works for elements, but since the element variable is an element, we can safely use it here.
I've also added an additional test.
I don't think we had this issue in v4, since we relied on jQuery back then.
Ref. https://developer.mozilla.org/en-US/docs/Web/API/NonDocumentTypeChildNode/nextElementSibling
- v4 (jQuery): https://getbootstrap.com/docs/4.4/components/scrollspy/#example-with-nested-nav
- v5 (broken): https://twbs-bootstrap.netlify.com/docs/4.3/components/scrollspy/#example-with-nested-nav
- v5 (fixed): https://deploy-preview-30117--twbs-bootstrap.netlify.com/docs/4.3/components/scrollspy/#example-with-nested-nav