Why not allow rendering undefined in JSX?

[park-jemin]

In JSX, do not render falsy values other than null.

Is there a reason undefined is excluded? I recall there being issues with it in older versions, but wasn't this was also patched years ago?

[kentcdodds]

I think it’s probably fine, can you share a code example of what rendering undefined would look like and why I’d do that instead of null?

[park-jemin]

I've seen something like this pretty commonly:

function Component() {
  const data = await getData();

  return (
     <div>
       {data?.map(...)}
     </div>
   )
}

Having to force this to render null instead (whether via ternary, falsy check, or ??) feels like adding an unnecessary layer of indirection here imho, but wanna hear your thoughts on this

[kentcdodds]

Hmmm… I’ve probably done something like that before. We gotta think of a real situation though. Normally it’ll just be an empty array or I’ll want to display something else.