Cannot find an element via JavaScript which does exist

Development
2

Your script is loading before most of the page is rendered, so it can’t find the element…

This should get you what you’re looking for…

<script type="text/discourse-plugin" version="0.9">
api.onPageChange(() => {
  let currentRouteParent = api.container.lookup("router:main").currentRoute?.parent;
    if (currentRouteParent.name.includes("user")) {
        let userBg = currentRouteParent.attributes.profile_background_upload_url;

        if (userBg) {
            document.documentElement.style.setProperty('--profile-bg-img', userBg);
        } else {
            document.documentElement.style.removeProperty('--profile-bg-img');
      }
    }
});
</script>

I assume you’re trying to reuse the user’s profile background on the profile page somewhere? otherwise this won’t stick around if you navigate away from a profile and refresh the page…