const bufferPx = 150 const observer = new IntersectionObserver((entries) => { for (const entry of entries) { const slug = entry.target.id const tocEntryElement = document.querySelector(`a[data-for="${slug}"]`) const windowHeight = entry.rootBounds?.height if (windowHeight && tocEntryElement) { if (entry.boundingClientRect.y < windowHeight) { tocEntryElement.classList.add("in-view") } else { tocEntryElement.classList.remove("in-view") } } } }) function toggleToc(this: HTMLElement) { this.classList.toggle("collapsed") const content = this.nextElementSibling as HTMLElement | undefined if (!content) return content.classList.toggle("collapsed") content.style.maxHeight = content.style.maxHeight === "0px" ? content.scrollHeight + "px" : "0px" } function setupToc() { const toc = document.getElementById("toc") if (toc) { const collapsed = toc.classList.contains("collapsed") const content = toc.nextElementSibling as HTMLElement | undefined if (!content) return content.style.maxHeight = collapsed ? "0px" : content.scrollHeight + "px" toc.removeEventListener("click", toggleToc) toc.addEventListener("click", toggleToc) } } window.addEventListener("resize", setupToc) document.addEventListener("nav", () => { setupToc() // update toc entry highlighting observer.disconnect() const headers = document.querySelectorAll("h1[id], h2[id], h3[id], h4[id], h5[id], h6[id]") headers.forEach((header) => observer.observe(header)) })