When unmounting components like this:

<form>
    <label for="exampleInputID">ID</label>
    <SomeUserDefinedComponent/>
</form>

SomeUserDefinedComponent = {
  render: function() {
    return <input/>;
  }
}

a memory leak happens because ReactMount.getID(node) puts DOM nodes back to nodeCache if they are not there.. just right after they were purged from cache.

To fix the leak there is a need for some read-only getID()..

Here is what's happing when unmounting that example component:

• label component gets purged from nodeCache
• when ReactDOMInput component is going to unmount it calls this method:

  componentWillUnmount: function() {
    var rootNode = this.getDOMNode();
    var id = ReactMount.getID(rootNode);
    delete instancesByReactID[id];
  }

which contains this.getDOMNode() which iterates through the children of the Form element calling getID() on each of them.. which puts these elements back into the cache.

So first they were purged and here they are all put back in cache causing a memory leak :(

I'm playing with React just 3rd day so not sure of a way to correctly fix this issue