[talmand]

What was ReactJS doing a few years ago that was wrong then but correct now? Since I don't know what that is, did the spec change during that time?

As far as I know right now, custom attributes goes against the html standard.

[RobertRoberts]

>What was ReactJS doing a few years ago that was wrong then but correct now?

Inline styles for one... created with javascript no less. This was totally verboten not long ago. But then became a "best practice" only because React started doing it.

[talmand]

I disagree, inline styles is never a "best practice" no matter what the reason or who does it. It happens from time-to-time due to necessity, but that doesn't make it best practice. In this case, React is simply doing it wrong.