支持React16的组件返回数组或简单类型的行为 about anu HOT 3 CLOSED

updateChildren: function (prevChildren, nextChildren, mountImages, removedNodes, transaction, hostParent, hostContainerInfo, context, selfDebugID) // 0 in production and for roots
  {
    // We currently don't have a way to track moves here but if we use iterators
    // instead of for..in we can zip the iterators and check if an item has
    // moved.
    // TODO: If nothing has changed, return the prevChildren object so that we
    // can quickly bailout if nothing has changed.
    if (!nextChildren && !prevChildren) {
      return;
    }
    var name;
    var prevChild;
    for (name in nextChildren) {
      if (!nextChildren.hasOwnProperty(name)) {
        continue;
      }
      prevChild = prevChildren && prevChildren[name];
      var prevElement = prevChild && prevChild._currentElement;
      var nextElement = nextChildren[name];
      if (prevChild != null && shouldUpdateReactComponent(prevElement, nextElement)) {
        ReactReconciler.receiveComponent(prevChild, nextElement, transaction, context);
        nextChildren[name] = prevChild;
      } else {
        if (prevChild) {
          removedNodes[name] = ReactReconciler.getHostNode(prevChild);
          ReactReconciler.unmountComponent(prevChild, false);
        }
        // The child must be instantiated before it's mounted.
        var nextChildInstance = instantiateReactComponent(nextElement, true);
        nextChildren[name] = nextChildInstance;
        // Creating mount image now ensures refs are resolved in right order
        // (see https://github.com/facebook/react/pull/7101 for explanation).
        var nextChildMountImage = ReactReconciler.mountComponent(nextChildInstance, transaction, hostParent, hostContainerInfo, context, selfDebugID);
        mountImages.push(nextChildMountImage);
      }
    }
    // Unmount children that are no longer present.
    for (name in prevChildren) {
      if (prevChildren.hasOwnProperty(name) && !(nextChildren && nextChildren.hasOwnProperty(name))) {
        prevChild = prevChildren[name];
        removedNodes[name] = ReactReconciler.getHostNode(prevChild);
        ReactReconciler.unmountComponent(prevChild, false);
      }
    }
  },


_updateChildren: function (nextNestedChildrenElements, transaction, context) {
      var prevChildren = this._renderedChildren;
      var removedNodes = {};
      var mountImages = [];
      var nextChildren = this._reconcilerUpdateChildren(prevChildren, nextNestedChildrenElements, mountImages, removedNodes, transaction, context);
      if (!nextChildren && !prevChildren) {
        return;
      }
      var updates = null;
      var name;
      // `nextIndex` will increment for each child in `nextChildren`, but
      // `lastIndex` will be the last index visited in `prevChildren`.
      var nextIndex = 0;
      var lastIndex = 0;
      // `nextMountIndex` will increment for each newly mounted child.
      var nextMountIndex = 0;
      var lastPlacedNode = null;
      for (name in nextChildren) {
        if (!nextChildren.hasOwnProperty(name)) {
          continue;
        }
        var prevChild = prevChildren && prevChildren[name];
        var nextChild = nextChildren[name];
        if (prevChild === nextChild) {
          updates = enqueue(updates, this.moveChild(prevChild, lastPlacedNode, nextIndex, lastIndex));
          lastIndex = Math.max(prevChild._mountIndex, lastIndex);
          prevChild._mountIndex = nextIndex;
        } else {
          if (prevChild) {
            // Update `lastIndex` before `_mountIndex` gets unset by unmounting.
            lastIndex = Math.max(prevChild._mountIndex, lastIndex);
            // The `removedNodes` loop below will actually remove the child.
          }
          // The child must be instantiated before it's mounted.
          updates = enqueue(updates, this._mountChildAtIndex(nextChild, mountImages[nextMountIndex], lastPlacedNode, nextIndex, transaction, context));
          nextMountIndex++;
        }
        nextIndex++;
        lastPlacedNode = ReactReconciler.getHostNode(nextChild);
      }
      // Remove children that are no longer present.
      for (name in removedNodes) {
        if (removedNodes.hasOwnProperty(name)) {
          updates = enqueue(updates, this._unmountChild(prevChildren[name], removedNodes[name]));
        }
      }
      if (updates) {
        processQueue(this, updates);
      }
      this._renderedChildren = nextChildren;

      if ("development" !== 'production') {
        setChildrenForInstrumentation.call(this, nextChildren);
      }
    },

function Unique() {
    if (typeof Set === "function") {
        return new Set();
    } else {
        return new innerSet();
    }
}
function innerSet() {
    this.array = [];
}
innerSet.prototype = {
    has: function(a) {
        return this.array.indexOf(a) > -1;
    },
    add: function(a) {
        if (!this.has(a)) {
            this.array.push(a);
        }
    }
};