32 lines
587 B
JavaScript
32 lines
587 B
JavaScript
headings = [];
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onload = function(){
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headings = document.querySelectorAll('h2');
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};
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onscroll = function(e){
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var heading = find(window.scrollY);
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if (!heading) return;
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var links = document.querySelectorAll('#menu a')
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, link;
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for (var i = 0, len = links.length; i < len; ++i) {
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link = links[i];
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link.className = link.getAttribute('href') == '#' + heading.id
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? 'active'
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: '';
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}
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};
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function find(y) {
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var i = headings.length
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, heading;
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while (i--) {
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heading = headings[i];
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if (y > heading.offsetTop) {
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return heading;
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}
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}
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}
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