Function FiberNode

docs/external/js/react-dom.development.js:23711–23782

(tag, pendingProps, key, mode)

  var debugCounter = 1;

  function FiberNode(tag, pendingProps, key, mode) {
    // Instance
    this.tag = tag;
    this.key = key;
    this.elementType = null;
    this.type = null;
    this.stateNode = null; // Fiber

    this.return = null;
    this.child = null;
    this.sibling = null;
    this.index = 0;
    this.ref = null;
    this.pendingProps = pendingProps;
    this.memoizedProps = null;
    this.updateQueue = null;
    this.memoizedState = null;
    this.dependencies = null;
    this.mode = mode; // Effects

    this.effectTag = NoEffect;
    this.nextEffect = null;
    this.firstEffect = null;
    this.lastEffect = null;
    this.expirationTime = NoWork;
    this.childExpirationTime = NoWork;
    this.alternate = null;

    {
      // Note: The following is done to avoid a v8 performance cliff.
      //
      // Initializing the fields below to smis and later updating them with
      // double values will cause Fibers to end up having separate shapes.
      // This behavior/bug has something to do with Object.preventExtension().
      // Fortunately this only impacts DEV builds.
      // Unfortunately it makes React unusably slow for some applications.
      // To work around this, initialize the fields below with doubles.
      //
      // Learn more about this here:
      // https://github.com/facebook/react/issues/14365
      // https://bugs.chromium.org/p/v8/issues/detail?id=8538
      this.actualDuration = Number.NaN;
      this.actualStartTime = Number.NaN;
      this.selfBaseDuration = Number.NaN;
      this.treeBaseDuration = Number.NaN; // It's okay to replace the initial doubles with smis after initialization.
      // This won't trigger the performance cliff mentioned above,
      // and it simplifies other profiler code (including DevTools).

      this.actualDuration = 0;
      this.actualStartTime = -1;
      this.selfBaseDuration = 0;
      this.treeBaseDuration = 0;
    } // This is normally DEV-only except www when it adds listeners.
    // TODO: remove the User Timing integration in favor of Root Events.


    {
      this._debugID = debugCounter++;