Math.easeInOutQuad = function (t: number, b: number, c: number, d: number) {
|
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: number, duration: number, callback: () => void) {
|
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();
|
}
|
