Type Alias StrictExclude<T, U>

StrictExclude: Exclude<T, U>

A stricter version of Exclude that enforces valid exclusion shapes.

StrictExclude tries to prevent accidentally excluding values that could never exist in T.

Type Parameters

T
The source union type
U extends ExcludeExtractConstraint<T>
The exclusion type (must conform to T)

Example: Basic usage (same as `Exclude`)

type Result = StrictExclude<"a" | "b" | "c", "a">;
//   ^?
// "b" | "c"

Example: Excluding a union member by shape

type Input =
  | { type: "a"; value: string }
  | { type: "b"; value: number };

type Result = StrictExclude<Input, { type: "a" }>;
//   ^?
// { type: "b"; value: number }

Example: Invalid exclusion is rejected

type Input =
  | { a: string }
  | { b: number };

type Invalid = StrictExclude<
  Input,
  //@ts-expect-error - not compatible with any member of Input
  { c: boolean }
>;