const easeInOutQuad = (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
|
const requestAnimFrame = (function () {
|
return (
|
window.requestAnimationFrame ||
|
(window as any).webkitRequestAnimationFrame ||
|
(window as any).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
|
*/
|
const move = (amount: number) => {
|
document.documentElement.scrollTop = amount;
|
(document.body.parentNode as HTMLElement).scrollTop = amount;
|
document.body.scrollTop = amount;
|
};
|
|
const position = () => {
|
return document.documentElement.scrollTop || (document.body.parentNode as HTMLElement).scrollTop || document.body.scrollTop;
|
};
|
|
/**
|
* @param {number} to
|
* @param {number} duration
|
* @param {Function} callback
|
*/
|
export const scrollTo = (to: number, duration: number, callback?: any) => {
|
const start = position();
|
const change = to - start;
|
const increment = 20;
|
let currentTime = 0;
|
duration = typeof duration === 'undefined' ? 500 : duration;
|
const animateScroll = function () {
|
// increment the time
|
currentTime += increment;
|
// find the value with the quadratic in-out easing function
|
const val = 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();
|
};
|
