55 lines
2.3 KiB
Handlebars
55 lines
2.3 KiB
Handlebars
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// Populate the sidebar
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//
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// This is a script, and not included directly in the page, to control the total size of the book.
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// The TOC contains an entry for each page, so if each page includes a copy of the TOC,
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// the total size of the page becomes O(n**2).
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var sidebarScrollbox = document.querySelector("#sidebar .sidebar-scrollbox");
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sidebarScrollbox.innerHTML = '{{#toc}}{{/toc}}';
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(function() {
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let current_page = document.location.href.toString();
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if (current_page.endsWith("/")) {
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current_page += "index.html";
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}
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var links = sidebarScrollbox.querySelectorAll("a");
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var l = links.length;
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for (var i = 0; i < l; ++i) {
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var link = links[i];
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var href = link.getAttribute("href");
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if (href && !href.startsWith("#") && !/^(?:[a-z+]+:)?\/\//.test(href)) {
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link.href = path_to_root + href;
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}
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// The "index" page is supposed to alias the first chapter in the book.
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if (link.href === current_page || (i === 0 && path_to_root === "" && current_page.endsWith("/index.html"))) {
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link.classList.add("active");
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var parent = link.parentElement;
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while (parent) {
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if (parent.tagName === "LI" && parent.previousElementSibling) {
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if (parent.previousElementSibling.classList.contains("chapter-item")) {
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parent.previousElementSibling.classList.add("expanded");
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}
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}
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parent = parent.parentElement;
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}
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}
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}
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})();
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// Track and set sidebar scroll position
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sidebarScrollbox.addEventListener('click', function(e) {
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if (e.target.tagName === 'A') {
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sessionStorage.setItem('sidebar-scroll', sidebarScrollbox.scrollTop);
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}
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}, { passive: true });
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var sidebarScrollTop = sessionStorage.getItem('sidebar-scroll');
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sessionStorage.removeItem('sidebar-scroll');
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if (sidebarScrollTop) {
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// preserve sidebar scroll position when navigating via links within sidebar
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sidebarScrollbox.scrollTop = sidebarScrollTop;
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} else {
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// scroll sidebar to current active section when navigating via "next/previous chapter" buttons
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var activeSection = document.querySelector('#sidebar .active');
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if (activeSection) {
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activeSection.scrollIntoView({ block: 'center' });
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}
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}
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