76 lines
2.6 KiB
JavaScript
76 lines
2.6 KiB
JavaScript
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// Auto generate table of contents
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// Code based on https://techindetail.com/table-of-contents-javascript/
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window.addEventListener('DOMContentLoaded', (event) => {
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const article = document.querySelector("article");
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const headings = article.querySelectorAll("h2, h3");
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const toc = document.querySelector(".toc");
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const tocSidebar = document.querySelector(".sidebar__toc");
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const leftSidebar = document.querySelector('.left-sidebar');
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const totalHeadings = headings.length;
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let tocOl = document.createElement("ol");
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let tocFragment = new DocumentFragment();
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let mainLi = null;
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let subUl = null;
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let subLi = null;
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let isSibling = false;
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if (totalHeadings > 1) {
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for (let element of headings) {
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let anchor = document.createElement("a");
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let anchorText = element.innerText;
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anchor.innerText = anchorText;
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let elementId = anchorText.replaceAll(" ", "-").toLowerCase();
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anchor.href = "#" + elementId;
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element.id = elementId;
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let level = element.nodeName;
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if ("H3" === level) {
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if (mainLi) {
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subLi = document.createElement("li");
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subLi.appendChild(anchor);
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if (isSibling === false) {
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subUl = document.createElement("ul");
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}
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subUl.appendChild(subLi);
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mainLi.appendChild(subUl);
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isSibling = true;
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}
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} else {
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mainLi = document.createElement("li");
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mainLi.appendChild(anchor);
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tocFragment.appendChild(mainLi);
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isSibling = false;
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subUl = null;
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}
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}
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tocOl.append(tocFragment);
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toc.append(tocOl);
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const tocClone = tocOl.cloneNode(true);
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if (tocSidebar) {
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tocSidebar.appendChild(tocClone);
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}
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} else {
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toc.classList.add('hidden');
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leftSidebar.classList.add('hidden');
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}
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// Close article ToC accordion and the left sidebar for small screen sizes
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if (window.innerWidth < 480) {
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toc.removeAttribute("open");
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leftSidebar.classList.add("hidden");
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} else {
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toc.setAttribute("open", true);
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}
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// Remove the stickiness of the sidebar ToC if it is larger than screen height
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function preventSidebarOverflow() {
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if (document.documentElement.clientHeight < tocSidebar.offsetHeight + 50) {
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tocSidebar.style.marginTop = "0";
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tocSidebar.style.position = "static";
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}
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}
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preventSidebarOverflow();
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});
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