do-momentum.js

rflect.ui.MomentumScroller.prototype.doMomentum = function() {
  // Calculate the movement properties. Implement getEndVelocity using the
  // start and end position / time.
  var velocity = this.getEndVelocity();
  if (velocity != 0) {
    var acceleration = this.getAcceleration(velocity);
    var displacement = - (velocity * velocity) / (2 * acceleration);
    var time = - velocity / acceleration;

    var newY = this.contentOffsetY + displacement;

    if (this.positionIsOutOfBounds(newY)) {

      this.setUpTransitionStage1();

    } else {

      // Set up the transition and execute the transform. Once you implement this
      // you will need to figure out an appropriate time to clear the transition
      // so that it doesn’t apply to subsequent scrolling.
      let transition =
          rflect.browser.css.getSelectorCasedProperty('transform') + ' ' +
          time + 'ms cubic-bezier(0.33, 0.66, 0.66, 1)';

      rflect.browser.css.setTransition(this.element, transition);
      rflect.browser.css.setTransition(this.getScrollBarContainer(), transition);
      this.contentOffsetY = newY;
      rflect.browser.css.setTransform(this.element,
          `translate3d(0, ${newY}px, 0)`);
      rflect.browser.css.setTransform(this.getScrollBarContainer(),
          `translate3d(0, ${-(newY / this.getSizeRatio() -
          this.getScrollBarLineHeight() / 2)}px, 0)`);
    }

    this.isDecelerating_ = true;
  } else {
    this.showScrollBarDelayed(false);
  }
}