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(function () { |
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'use strict'; |
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|
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function reducedMotion() { |
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return window.matchMedia && window.matchMedia('(prefers-reduced-motion: reduce)').matches; |
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} |
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|
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function reveal(units) { |
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// CSS stagger is driven by --bkst-i custom property; just add class |
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units.forEach(function (unit) { |
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unit.classList.add('bkst-revealed'); |
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}); |
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} |
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|
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function hide(units) { |
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units.forEach(function (unit) { |
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unit.classList.remove('bkst-revealed'); |
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}); |
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} |
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|
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function getUnits(section) { |
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var split = section.dataset.split || 'words'; |
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var sel = split === 'chars' ? '.bkst-char' : split === 'lines' ? '.bkst-line' : '.bkst-word'; |
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return Array.prototype.slice.call(section.querySelectorAll(sel)); |
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} |
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|
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function initSection(section) { |
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var threshold = parseFloat(section.dataset.threshold) || 0.15; |
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var repeat = section.dataset.repeat === 'true'; |
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|
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if (reducedMotion()) { |
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// Show all immediately |
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var allUnits = Array.prototype.slice.call(section.querySelectorAll('.bkst-word,.bkst-char,.bkst-line')); |
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reveal(allUnits); |
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return; |
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} |
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|
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var units = getUnits(section); |
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var stagger = parseFloat(section.dataset.stagger) || 80; |
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|
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// Set CSS custom property --bkst-i on each unit for stagger timing |
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units.forEach(function (unit, i) { |
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unit.style.setProperty('--bkst-i', i); |
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}); |
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|
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var observer = new IntersectionObserver(function (entries) { |
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entries.forEach(function (entry) { |
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if (entry.isIntersecting) { |
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reveal(units); |
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if (!repeat) observer.unobserve(section); |
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} else if (repeat) { |
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hide(units); |
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} |
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}); |
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}, { threshold: threshold }); |
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|
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observer.observe(section); |
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} |
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|
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function init() { |
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document.querySelectorAll('.bkst-section[data-animation]').forEach(initSection); |
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} |
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|
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if (typeof IntersectionObserver === 'undefined') { |
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// Fallback for very old browsers |
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document.querySelectorAll('.bkst-word,.bkst-char,.bkst-line').forEach(function (el) { |
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el.classList.add('bkst-revealed'); |
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}); |
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return; |
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} |
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|
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if (document.readyState === 'loading') { |
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document.addEventListener('DOMContentLoaded', init); |
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} else { |
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init(); |
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} |
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|
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}()); |
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|
