Smooth scroll animation using the Ease In Quint function.

scrolling.js

const scrollToElement = (id) => {
  let duration       = 1000;
  let element        = document.getElementById(id);
  if (!element)
    return;
  let targetPosition = element.offsetTop;
  let startPosition  = window.pageYOffset;
  let distance       = targetPosition - startPosition;
  let startTime      = null;

  const animate = (currentTime) => {
    if (startTime === null) {
        startTime = currentTime;
    }
    let timeElapsed = currentTime - startTime;
    let run         = easeInOutQuint(timeElapsed, startPosition, distance, duration);
    window.scrollTo(0, run);

    if (timeElapsed < duration) {
        requestAnimationFrame(animate);
    }
  }

  const easeInOutQuint = (t, b, c, d) => {
    t /= d/2;
    if (t < 1 ) {
        return c/2*t*t*t*t*t + b;
    }
    t -= 2;
    return c/2*(t*t*t*t*t + 2) + b;
  }

  requestAnimationFrame(animate);
}

// Example scrollToElement("elementId");