Returning null from getDerivedStateFromProps is causing updates

Do you want to request a feature or report a bug?

Bug

What is the current behavior?

Returning null from getDerivedStateFromProps triggers updates and componentDidUpdate is being called.

If the current behavior is a bug, please provide the steps to reproduce and if possible a minimal demo of the problem. Your bug will get fixed much faster if we can run your code and it doesn’t have dependencies other than React. Paste the link to your JSFiddle (https://jsfiddle.net/Luktwrdm/) or CodeSandbox (https://codesandbox.io/s/new) example below:

https://jsfiddle.net/69z2wepo/328290/

What is the expected behavior?

componentDidUpdate and render methods should not be called.

[nkprince007]

At the very least, the documentation should mention that this is intentional and “update nothing” doesn’t mean that componentDidUpdate and render won’t be called. It is very confusing when the method specifically asks us to return null in case of no updates.

[jquense]

The state is left unchanged when you return null. The reason you return null, is that it’s a clear signal to react that you intend to not update state, whereas undefined could indicate you do want to update but forgot to return anything. Components should continue to update tho as render may depend on new props even if state doesn’t. If you want to prevent updates shouldComponentUpdate is the hook for that.