What does TypeScript’s ‘exactOptionalPropertyTypes’ flag change about the following type? interface Config { timeout?: number; }

TypeScript Professional Hard

TypeScript Professional — Hard

What does TypeScript’s ‘exactOptionalPropertyTypes’ flag change about the following type? interface Config { timeout?: number; }

Key points

  • The flag enforces a distinction between 'absent' and 'undefined'
  • It requires explicit 'undefined' for optional properties
  • Setting a property to 'undefined' without the flag is considered an error
  • The flag ensures more precise type checking for optional properties

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