DatePicker: onChange should not have date argument as optional

[veekeys]

This does not really make sense as on change will always return date. Also, it makes usage of date picker not nice as you need to save variable with Date | undefined type. Just this change might be done only on v2 as it looks like a breaking one..

[mayank99]

How is it a breaking change? You can make it not optional and it should not change usage.

You would still be able to do this:

onChange={() => {}}

Here's an example from Select (the value arg is not optional): https://github.com/iTwin/iTwinUI-react/blob/b863b1d8917be9b64954bce03d75f60eb5f80d7a/src/core/Select/Select.tsx#L69

and here is one from Button:

[veekeys]

Simply.

[mayank99]

That would still not be a breaking change. If the users are already setting type of their state as Date | undefined, then narrowing down the type would still be valid.

[veekeys]

So breaking the build after library update now is not considered as breaking change?

[veekeys]

Ok, might be not a breaking change after all... We can make this fix.