[material-ui][InputBase] onBlur called with undefined event contrary to type definition

[sydneyjodon-wk]

Hello 👋

Search keywords

undefined event onBlur

Latest version

• I have tested the latest version

Steps to reproduce

Steps:

1. Open this link to live example: https://stackblitz.com/edit/react-zufzmfhc?file=Demo.tsx
2. Type something in the input
3. See in the console that the event passed to onBlur is undefined if the InputBase is disabled

Current behavior

InputBase is calling onBlur with an undefined event in certain cases, but the type definition for onBlur does not have a nullable event:

/**
* Callback fired when the `input` is blurred.
*
* Notice that the first argument (event) might be undefined.
*/
onBlur?: React.FocusEventHandler<HTMLInputElement | HTMLTextAreaElement>;

Even though there is a comment, undefined is not an option for the events.

Expected behavior

I would have expected the behavior of the onBlur to match the type definition and no undefined event to be passed in. Would it be possible to either update the type definition to include undefined or update the onBlur call to pass in an event for InputBase?

Context

We are running with strict null safety and this is causing an issue.

Your environment

See sandbox: https://stackblitz.com/edit/react-zufzmfhc?file=Demo.tsx

Thank you!

[ZeeshanTamboli]

I think we can add undefined to onBlur parameter type since we can’t pass the event to it inside useEffect.

Hopefully it won’t be a breaking change. Want to give it a try and open a PR?

[ZeeshanTamboli]

As expected, this would be a breaking change (See #45994 (review)) Won't just the JSDoc already mentioning that the event might be undefined work for you?

Unfortunately, we can't add this change.

[sydneyjodon-wk]

@ZeeshanTamboli thank you for trying! Our code is expecting the typing to be honored strictly so the fact that undefined is being passed in when the type says that it never will be is throwing for us so just having a doc comment isn't enough. It's okay though - we will work around it on our end. Would it be possible to consider adding this to the next major?

[ZeeshanTamboli]

Would it be possible to consider adding this to the next major?

Yes, we can.

[sydneyjodon-wk]

Thank you!!