a native scrollTo function in javascript that uses requestAnimationFrame and easing for animation

scrollTo.js

// easing functions http://goo.gl/5HLl8
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;
};

Math.easeInCubic = function(t, b, c, d) {
  var tc = (t/=d)*t*t;
  return b+c*(tc);
};

Math.inOutQuintic = function(t, b, c, d) {
  var ts = (t/=d)*t,
  tc = ts*t;
  return b+c*(6*tc*ts + -15*ts*ts + 10*tc);
};

// 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); };
})();

function scrollTo(to, callback, duration) {
  // because it's so fucking difficult to detect the scrolling element, just move them all
  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;
  }
  var start = position(),
    change = to - start,
    currentTime = 0,
    increment = 20;
  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();
}

"because it's so fucking difficult to detect the scrolling element, just move them all"

False! Thanks for this Gist 👍

---

document.scrollingElement

...for legacies:

do {
  if (element.clientHeight < element.scrollHeight || element.clientWidth < element.scrollWidth) {
    return element
  }
} while (element = element.parentNode)

I quickly translated this for Angular 2 and/or Angular 4:

import { Injectable, ElementRef } from '@angular/core';

@Injectable()
export class ScrollToService {

    constructor() {}

    // easing functions http://goo.gl/5HLl8
    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;
    };

    easeInCubic = function(t, b, c, d) {
        var tc = (t/=d)*t*t;
        return b+c*(tc);
    };

    inOutQuintic = function(t, b, c, d) {
        var ts = (t/=d)*t,
        tc = ts*t;
        return b+c*(6*tc*ts + -15*ts*ts + 10*tc);
    };

    scrollTo(to: number, callback: any, duration: number) {
        function move(amount) {
            document.documentElement.scrollTop = amount;
            (<Element>document.body.parentNode).scrollTop = amount;
            document.body.scrollTop = amount;
        }
        function position() {
            return document.documentElement.scrollTop || (<Element>document.body.parentNode).scrollTop || document.body.scrollTop;
        }
        let animationFrameReqFunc = window.requestAnimationFrame || window.webkitRequestAnimationFrame || (<any>window).mozRequestAnimationFrame || function( callback ){ window.setTimeout(callback, 1000 / 60); };
        let start = position(),
        change = to - start,
        currentTime = 0,
        increment = 20;
        duration = (typeof(duration) === 'undefined') ? 500 : duration;
        let animateScroll = () => {
            // increment the time
            currentTime += increment;
            // find the value with the quadratic in-out easing function
            let val = this.easeInCubic(currentTime, start, change, duration);
            // move the document.body
            move(val);
            // do the animation unless its over
            if (currentTime < duration) {
                animationFrameReqFunc(animateScroll);
            } else {
                if (callback && typeof(callback) === 'function') {
                    // the animation is done so lets callback
                    callback();
                }
            }
        };
        animateScroll();
    }
}

I found an other solution much simpler:

/**
 *  Scroll to element, for now it scroll to Top.
 * @param duration default 1000ms
 */
export const scrollToElement = (duration = 1000) => {
  let cosParameter = window.scrollY / 2
  let scrollCount = 0
  let oldTimestamp = performance.now()

  function step (newTimestamp) {
    scrollCount += Math.PI / (duration / (newTimestamp - oldTimestamp))
    if (scrollCount >= Math.PI) window.scrollTo(0, 0)
    if (window.scrollY === 0) return
    window.scrollTo(0, Math.round(cosParameter + cosParameter * Math.cos(scrollCount)))
    oldTimestamp = newTimestamp
    window.requestAnimationFrame(step)
  }

  window.requestAnimationFrame(step)
}

shouldn't time be calculated from the timestamp passed to the raf callback? As in the example https://developer.mozilla.org/en-US/docs/Web/API/window/requestAnimationFrame?

Thank you man, you saved my ass after I run out of options for pulling out cross browser compatible animation. I lost like 5 hours in frustration, and your solution works best.