Function getTransitionsForLanes

packages/react-reconciler/src/ReactFiberLane.js:1222–1249

(
  root: FiberRoot,
  lanes: Lane | Lanes,
)

}

export function getTransitionsForLanes(
  root: FiberRoot,
  lanes: Lane | Lanes,
): Array<Transition> | null {
  if (!enableTransitionTracing) {
    return null;
  }

  const transitionsForLanes = [];
  while (lanes > 0) {
    const index = laneToIndex(lanes);
    const lane = 1 << index;
    const transitions = root.transitionLanes[index];
    if (transitions !== null) {
      transitions.forEach(transition => {
        transitionsForLanes.push(transition);
      });
    }

    lanes &= ~lane;
  }

  if (transitionsForLanes.length === 0) {
    return null;
  }

  return transitionsForLanes;
}

export function clearTransitionsForLanes(root: FiberRoot, lanes: Lane | Lanes) {
  if (!enableTransitionTracing) {