defaultChecked prop sets only checked attribute

[klintmane]

Type

inconsistency for common use cases.
bug for projects relying on correct DOM emissions.

Description

It's unclear to me if the following is a known issue or not.
Take in consideration the snippet below:

<input type="checkbox" defaultChecked={true} />

Current Behavior

Setting the defaultValue prop on inputs of other types sets both the value and defaultValue attribute on the DOM element.

When setting the defaultChecked prop on inputs of type checkbox only the checked attribute is correctly set, leaving the defaultChecked attribute unchanged.

Expected Behaviour

Like mentioned above, the expected behavior would be for the defaultChecked prop to set both the checked and defaultChecked attributes on the corresponding DOM node (like it's the case with the defaultValue prop).

[Checkson]

I also found the same problem, I am now very distressed, ask how to solve？

[nhunzaker]

This does appear to be a bug: https://codesandbox.io/s/qx0110rpo6

The "checked" attribute is not initially set on the input:

<input type="checkbox" defaultChecked={true} />

It looks like this has been a bug since 15.0.0. I think we need to add/remove the checked attribute in the post-mount wrapper:
https://github.com/facebook/react/blob/master/packages/react-dom/src/client/ReactDOMFiberInput.js#L245-L246

[nhunzaker]

Fixed by #13114