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Check Authorization With Types (again)

@RiccardoOdone•Suggest a tip•

Moving authorization from value to type level can make your code simpler and bullet-proof.

const dropDatabase = (performedBy: User) => {
  if (performedBy._kind !== 'user') { return } // ⛔️ Should be ===
  // ...
}

dropDatabase(member) // ⛔️

type MemberKind = "user"
type User = { _kind: "admin" } | { _kind: "editor" } | { _kind: MemberKind }
type FilterPrivileged<U extends User> = U extends { _kind: MemberKind } ? never : U
type Privileged = FilterPrivileged<User>

const dropDatabase = (performedBy: Privileged) => {
  // ...
}

dropDatabase(member) // ✅ Does not compile
Type-safe carouselDo not throwFilter using a type assertionUse precise typesType-safe string templatingEnumerating a union typeNumbers with unitsZero nullEnumerating statusesAnd typesAvoiding window as anyUse descriptive valuesCheck authorization with typesExtract union types from record typesKeep in sync with conditional typesType-safe pickPass arguments by namePick instead of duplicatingPrevent mutationsType aliasesModel with different typesPrefer static types over testsPush conditionals downType-level functionsCheck Authorization With Types (again)From Union to TupleLimit typesLaser-focused typesCallable typesPartial considered harmfulSatisfy typesWTH?!Parse, don't castNarrow typesFetch footgunModel with different types (2)Polymorphic typesParse, don't cast (again)Type-safe envObject vs Recordconst Type ParametersDigType checksExpand intellisenseNumbers with units (2)Unchecked indexed accessExtract instead of duplicating

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