How unique should a React component Key be?

Question

This is a quick one: what is the scope in which the children keys have to be unique? Is this just the parent component or the whole app?

If the latter is true, does

Answer 1

Yes, looks like it...if you re-parent it, it'll give a different reactid (eg. http://webcloud.se/react-sortable/nested.html )

and will unmount/re-mount again. ...

http://jsfiddle.net/46x0j6uq/1/

,componentWillUnmount: function() {
 //console.log("unmounted:", this.props);
 clearInterval(this.state.intervalId);
 clearTimeout(this.state.timeoutId);
}
,componentDidMount: function(){
  // console.log("mounted:", this.props);
  this.state.intervalId = setInterval(this.incrementCount, 1000);
 this.state.timeoutId = setTimeout(this.setColorToBlack, 300);
}

So, better not to store state in the view component itself, since it might reset itself. The above fiddle is just a demo to prove a point.

Other related links: Using keys to identify nested components in React.js

I did wish React had something to consider scoped/nested key states beyond the same level, but i guess the performance of unmounting/re-mounting again should hopefully not be too detrimental.