60 lines
1.6 KiB
HTML
60 lines
1.6 KiB
HTML
<style type="text/css" media="screen">
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.post-menu ul {
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list-style: none;
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padding: 0;
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margin: 0;
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}
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</style>
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<div class="post-menu">
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<div class="post-menu-title">Contents</div>
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<div class="post-menu-content"></div>
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</div>
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<script>
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var menu = document.querySelector(".post-menu .post-menu-content");
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var headings = document.querySelector(".post-content").querySelectorAll("h2, h3, h4, h5, h6");
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// Generate post menu
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var menuHTML = '';
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headings.forEach(function (h) {
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menuHTML += (
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'<li class="h-' + h.tagName.toLowerCase() + '">'
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+ '<a href="#h-' + h.getAttribute('id') + '">' + h.textContent + '</a></li>');
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});
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menu.innerHTML = '<ul>' + menuHTML + '</ul>';
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// The anchor offsetHeight
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var headerHeight = 0;
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var header = document.querySelector('header');
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if (header) {
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offsetHeight = header.offsetHeight + 12;
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}
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// Active the menu item
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window.addEventListener('scroll', function (event) {
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var lastActive = menu.querySelector('.active');
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var changed = true;
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for (var i = headings.length - 1; i >= 0; i--) {
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var h = headings[i];
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var clientRect = h.getBoundingClientRect();
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if (clientRect.top < offsetHeight) {
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var id = 'h-' + h.getAttribute('id');
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var curActive = menu.querySelector('a[href="#' + id + '"]');
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if (curActive) {
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curActive.classList.add('active');
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}
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if (lastActive == curActive) {
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changed = false;
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}
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break;
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}
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}
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if (lastActive && changed) {
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lastActive.classList.remove('active');
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}
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event.preventDefault();
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});
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</script>
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