If user dismisses the not topmost notification the timeout will be
cleared and a new one will not be set, because the top notification
remained the same (see the if at line 90).
The docs of 'componentDidUpdate' say that it's not called for the
initial render. If the component is added to the DOM with 1 notification
already, then the update will not happen and timeout will never be set
which will effectively break the timeouts chain.
paweldomas
hristoterezov
Bettenbuk Zoltan