Load more timeline items when clicking a link to an unloaded comment

[NicolasBonet]

Problem

On long issues and PRs, GitHub collapses the middle of the timeline behind a "N remaining items / Load more" control. Clicking a link to a comment on the same page (eg. #issuecomment-123 or https://github.com/org/repo/pull/1#discussion_r456) does nothing when that comment is inside the collapsed section, because the target isn't in the DOM yet.

Solution

Add loadMoreUntilAnchor, initialized on the issue and PR pages. It listens for plain left-clicks on links whose URL points at the current issue/PR path with a hash. If the target element (or its user-content- markdown heading variant) isn't in the DOM, it polls every 250ms:

1. If the target exists, scroll to it and stop.
2. Otherwise click every available load-more control: button[data-testid^="issue-timeline-load-more-"], button[data-testid="hidden-items-expander"] and button.ajax-pagination-btn, skipping ones that are disabled or have data-loading="true".

It stops after 30 seconds, after 3 seconds with no load-more control left, or when the user scrolls or presses a key. It runs independently of the auto load more comments preference.

Fixed Issues

None

Tests

1. Run npm run lint and confirm no errors.
2. Run npm run build and load dist as an unpacked extension.
3. Turn off the auto load more comments toggle.
4. Open a long issue or PR that shows "N remaining items".
5. Click a link on that page to a comment hidden in the collapsed section.
6. Confirm "Load more" is clicked repeatedly until the comment appears and the page scrolls to it.
7. Repeat step 5 and scroll the page while it is loading. Confirm loading stops and the page does not jump.
8. Click a link to a comment that is already visible. Confirm "Load more" is not clicked.

[os-botify]

🚀 Released in version 1.5.70 🚀