Improve readability of isValidElementType

[behnammodi]

isValidElementType is hard to understand and maintenance, so I tried to improve it

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[behnammodi]

I changed to switch/case

[rickhanlonii]

Not to nitpick, but since this is exclusively about readability, the switch statements are not as readable to me because they rely on fall throughs and no default cases, which I'm not used to when I read something like this.

What about just breaking the original into multiple ifs instead?

export default function isValidElementType(type: mixed) {
  if (typeof type === 'string' || typeof type === 'function') return true;

  // Note: typeof might be other than 'symbol' or 'number' (e.g. if it's a polyfill).
  if (
    type === REACT_FRAGMENT_TYPE ||
    type === REACT_PROFILER_TYPE ||
    type === REACT_DEBUG_TRACING_MODE_TYPE ||
    type === REACT_STRICT_MODE_TYPE ||
    type === REACT_SUSPENSE_TYPE ||
    type === REACT_SUSPENSE_LIST_TYPE ||
    type === REACT_LEGACY_HIDDEN_TYPE
  ) {
    return true;
  }

  if (typeof type === 'object' && type !== null) {
    if (
      type.$$typeof === REACT_LAZY_TYPE ||
      type.$$typeof === REACT_MEMO_TYPE ||
      type.$$typeof === REACT_PROVIDER_TYPE ||
      type.$$typeof === REACT_CONTEXT_TYPE ||
      type.$$typeof === REACT_FORWARD_REF_TYPE ||
      type.$$typeof === REACT_FUNDAMENTAL_TYPE ||
      type.$$typeof === REACT_RESPONDER_TYPE ||
      type.$$typeof === REACT_SCOPE_TYPE ||
      type.$$typeof === REACT_BLOCK_TYPE ||
      type[(0: any)] === REACT_SERVER_BLOCK_TYPE
    ) {
      return true;
    }
  }

  return false;
}

[behnammodi]

@rickhanlonii Nice, I will update it

[behnammodi]

@rickhanlonii I updated it.

[rickhanlonii]

LGTM

[gaearon]

I don't oppose merging this but for future reference — we don't normally take stylistic PRs. Style and "readability" are extremely subjective and these changes often introduce subtle mistakes.

isValidElementType is hard to understand and maintenance

As maintainers, we don't find this particular function hard to maintain. We appreciate your effort but I would suggest to focus on changes that aren't purely stylistic as those are unlikely to be merged in general.

[behnammodi]

@gaearon Thanks, sure