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