earthtoday-react-motion/src/shouldStopAnimation.js

A spring that solves your animation problems.

/* @flow */
import type { PlainStyle, Style, Velocity } from './Types';

// usage assumption: currentStyle values have already been rendered but it says
// nothing of whether currentStyle is stale (see unreadPropStyle)
export default function shouldStopAnimation(
  currentStyle: PlainStyle,
  style: Style,
  currentVelocity: Velocity,
): boolean {
  for (let key in style) {
    if (!Object.prototype.hasOwnProperty.call(style, key)) {
      continue;
    }

    if (currentVelocity[key] !== 0) {
      return false;
    }

    const styleValue =
      typeof style[key] === 'number' ? style[key] : style[key].val;
    // stepper will have already taken care of rounding precision errors, so
    // won't have such thing as 0.9999 !=== 1
    if (currentStyle[key] !== styleValue) {
      return false;
    }
  }

  return true;
}