JSX Spread tag proposal about jsx

[syranide]

I would say that spreading is not what you want, you want the same behavior as you would get with arrays (if you ignore the key warning) with it being its own hierarchy and implicit indices computed accordingly. A previously discussed syntax is <>, which is also consistent with E4X IIRC (for whatever it's worth).

Also, I imagine if we want to support spreading there's already a solution that wouldn't necessarily introduce new syntax <Parent>{...foobar}</Parent>. Again, not sure why you would want it though as opposed to just fragments.

[quassnoi]

Don't I have to key the fragments?

Actually come to think of it, <Parent>{...foobar}</Parent> would be nice too. That's what I was naively trying to do in the first place, only to stumble upon an error saying JSXSpreadAttribute being not in the right place. I just failed to find any proposals about this syntax or <>.

Is there any conceptual difference in React between

• createElement(tag, styles, a, b, c, d)
• createElement(tag, styles, a, [b, c], d)
• createElement(tag, styles, a, createFragment({b, c}), d)

?

[syranide]

Don't I have to key the fragments?

@quassnoi Using React.createFragment naively requires it yes, it's essentially an associative list (i.e. Map), so everything has to be keyed by necessity. But you could easily feed an array to React.createFragment (use index as key) or have JSX pre-compute the indices and assign keys accordingly.

I just failed to find any proposals about this syntax or <>.

Yeah, I'm not 100% sure TBH. It may just have been "informal/internal" discussions in other places.

Is there any conceptual difference in React between createElement(tag, styles, a, b, c, d) and createElement(tag, styles, a, [b, c], d)?

Yes, a very important one. Removing c in the non-array case would cause React to destroy the instance for d and try to reuse the instance for c but now with the props from d. In the second everything would happen just as you would normally expect.

[quassnoi]

Are you saying I can just pass an array to createFragment and it will accept it, keying by the index, with no extra effort from the developer's side?

[syranide]

@quassnoi Honestly not sure, but you could easily have a wrapper that does it, it's trivial logic.