59 lines
1.7 KiB
JavaScript
59 lines
1.7 KiB
JavaScript
Math.easeInOutQuad = function(t, b, c, d) {
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t /= d / 2
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if (t < 1) {
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return c / 2 * t * t + b
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}
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t--
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return -c / 2 * (t * (t - 2) - 1) + b
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}
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// requestAnimationFrame for Smart Animating http://goo.gl/sx5sts
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var requestAnimFrame = (function() {
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return window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame || function(callback) { window.setTimeout(callback, 1000 / 60) }
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})()
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/**
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* Because it's so fucking difficult to detect the scrolling element, just move them all
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* @param {number} amount
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*/
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function move(amount) {
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document.documentElement.scrollTop = amount
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document.body.parentNode.scrollTop = amount
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document.body.scrollTop = amount
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}
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function position() {
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return document.documentElement.scrollTop || document.body.parentNode.scrollTop || document.body.scrollTop
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}
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/**
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* @param {number} to
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* @param {number} duration
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* @param {Function} callback
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*/
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export function scrollTo(to, duration, callback) {
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const start = position()
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const change = to - start
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const increment = 20
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let currentTime = 0
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duration = (typeof (duration) === 'undefined') ? 500 : duration
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var animateScroll = function() {
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// increment the time
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currentTime += increment
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// find the value with the quadratic in-out easing function
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var val = Math.easeInOutQuad(currentTime, start, change, duration)
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// move the document.body
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move(val)
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// do the animation unless its over
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if (currentTime < duration) {
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requestAnimFrame(animateScroll)
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} else {
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if (callback && typeof (callback) === 'function') {
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// the animation is done so lets callback
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callback()
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}
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}
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}
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animateScroll()
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}
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