33 lines
856 B
JavaScript
33 lines
856 B
JavaScript
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// License: LGPL-3.0-or-later
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module.exports = function(el, className, parentClass) {
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var $el = $(el)
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var elPxFromTop = $el.offset().top
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var $parent = $el.parents(parentClass).length ? $el.parents(parentClass) : $el.parent()
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var parentHeightPlusTop = $parent.height() + $parent.offset().top - $el.height()
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var $elToToggle
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if (parentClass === undefined) {
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parentClass = ''
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$elToToggle = $el
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} else {
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$elToToggle = $parent
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}
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// the parentClass param is optional but if it is passed
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// then the className is applied to it instead of the el
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$(window).scroll(function() {
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var scrollPosition = $(window).scrollTop()
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if(scrollPosition >= elPxFromTop)
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$elToToggle.addClass(className)
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else
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$elToToggle.removeClass(className)
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if(parentClass && scrollPosition >= parentHeightPlusTop)
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$elToToggle.removeClass(className)
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})
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}
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