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Keep the Aliki TOC highlight in sync with the scroll position #1849

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Keep the Aliki TOC highlight in sync with the scroll position #1849

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154185e
Fix Aliki TOC highlighting and method group nesting
claude Oct 13, 2026
7d2b797
Leave Aliki TOC nesting to the heading level change
claude Oct 13, 2026
8512f01
Update the Aliki TOC highlight on resize
claude Oct 15, 2026
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58 changes: 27 additions & 31 deletions lib/rdoc/generator/template/aliki/js/aliki.js
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Original file line number Diff line number Diff line change
Expand Up @@ -305,28 +305,25 @@ function hookTocActiveHighlighting() {

if (targetHeadings.length === 0) return;

const observerOptions = {
root: null,
rootMargin: '0% 0px -35% 0px',
threshold: 0
};

const intersectingHeadings = new Set();
let activeLink = null;
const update = () => {
const firstIntersectingHeading = targetHeadings.find((heading) => {
return intersectingHeadings.has(heading);
});
if (!firstIntersectingHeading) return;
const correspondingLink = document.querySelector(`.toc-link[data-target="${firstIntersectingHeading.id}"]`);
if (!correspondingLink) return;

// Remove active class from all links
tocLinks.forEach((link) => {
link.classList.remove('active');
// Prefer the first heading in the upper 65% of the viewport. With no
// heading there, such as deep inside a long method list, the current
// section is the last heading above the viewport.
const viewportLimit = window.innerHeight * 0.65;
const currentHeading = targetHeadings.find((heading) => {
const rect = heading.getBoundingClientRect();
return rect.bottom > 0 && rect.top < viewportLimit;
}) || targetHeadings.findLast((heading) => {
return heading.getBoundingClientRect().top < 0;
});
if (!currentHeading) return;
const correspondingLink = document.querySelector(`.toc-link[data-target="${currentHeading.id}"]`);
if (!correspondingLink || correspondingLink === activeLink) return;

// Add active class to current link
activeLink?.classList.remove('active');
correspondingLink.classList.add('active');
activeLink = correspondingLink;

// Scroll link into view if needed
const tocNav = document.querySelector('#toc-nav');
Expand All @@ -339,21 +336,20 @@ function hookTocActiveHighlighting() {
}
}
};
const observer = new IntersectionObserver((entries) => {
entries.forEach((entry) => {
if (entry.isIntersecting) {
intersectingHeadings.add(entry.target);
} else {
intersectingHeadings.delete(entry.target);
}

let updateScheduled = false;
const scheduleUpdate = () => {
if (updateScheduled) return;
updateScheduled = true;
requestAnimationFrame(() => {
updateScheduled = false;
update();
});
update();
}, observerOptions);
};
window.addEventListener('scroll', scheduleUpdate, { passive: true });
window.addEventListener('resize', scheduleUpdate);

// Observe all headings that have corresponding TOC links
targetHeadings.forEach((heading) => {
observer.observe(heading);
});
update();
}

function setHeadingScrollHandler(heading, link) {
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