code: function getInstanceFromNode(node) {
    var inst = node[internalInstanceKey];
    if (inst) {
      if (inst.tag === HostComponent || inst.tag === HostText) {
        return inst;
      } else if (inst._hostNode === node) {
        return inst;
      } else {
        return null;
      }
    }
    inst = getClosestInstanceFromNode(node);
    if (inst != null && inst._hostNode === node) {
      return inst;
    } else {
      return null;
    }
  }
docs: Given a DOM node, return the ReactDOMComponent or ReactDOMTextComponent
  instance, or null if the node was not rendered by this React.