Function spring

Libraries/Animated/src/AnimatedImplementation.js:2015–2061

(
  value: AnimatedValue | AnimatedValueXY,
  config: SpringAnimationConfig,
)

};

var spring = function(
  value: AnimatedValue | AnimatedValueXY,
  config: SpringAnimationConfig,
): CompositeAnimation {
  var start = function(
    animatedValue: AnimatedValue | AnimatedValueXY,
    configuration: SpringAnimationConfig,
    callback?: ?EndCallback): void {
      callback = _combineCallbacks(callback, configuration);
      var singleValue: any = animatedValue;
      var singleConfig: any = configuration;
      singleValue.stopTracking();
      if (configuration.toValue instanceof Animated) {
        singleValue.track(new AnimatedTracking(
          singleValue,
          configuration.toValue,
          SpringAnimation,
          singleConfig,
          callback
        ));
      } else {
        singleValue.animate(new SpringAnimation(singleConfig), callback);
      }
  };
  return maybeVectorAnim(value, config, spring) || {
    start: function(callback?: ?EndCallback): void {
      start(value, config, callback);
    },

    stop: function(): void {
      value.stopAnimation();
    },

    reset: function(): void {
      value.resetAnimation();
    },

    _startNativeLoop: function(iterations?: number): void {
      var singleConfig = { ...config, iterations };
      start(value, singleConfig);
    },

    _isUsingNativeDriver: function(): boolean {
      return config.useNativeDriver || false;
    }
  };
};

var timing = function(
  value: AnimatedValue | AnimatedValueXY,