Created
July 15, 2016 16:32
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CoffeeScript cosine animated scroll class
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| class AnimatedScroll | |
| constructor: (scrollEnd, scrollDuration) -> | |
| @scrollStart = window.scrollY | |
| @scrollStep = Math.PI / scrollDuration | |
| @cosParameter = (@scrollStart - scrollEnd) / 2 | |
| @scrollEnd = scrollEnd | |
| @scrollDuration = scrollDuration | |
| @scrollCount = 0 | |
| @firstTs = null | |
| go: -> | |
| requestAnimationFrame(@step) | |
| step: (ts) => | |
| if not @firstTs | |
| @firstTs = ts | |
| animationTime = ts - @firstTs | |
| if animationTime <= @scrollDuration | |
| requestAnimationFrame(@step) | |
| scrollMargin = @cosParameter - @cosParameter * Math.cos( animationTime * @scrollStep ) | |
| window.scrollTo(0, @scrollStart - scrollMargin) | |
| else | |
| window.scrollTo(0, @scrollEnd) | |
| scrollToAnimated = (pos, duration) -> | |
| as = new AnimatedScroll(pos, duration) | |
| as.go() |
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