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Type Alias: RequiredIf<Value, ValueType, FallbackType>

RequiredIf<Value, ValueType, FallbackType> = If<Value, ValueType, ValueType | FallbackType>

Defined in: types.ts:283

A type utility that allows branching of an union type on the Value parameter.

Type Parameters​

Type ParameterDefault type
Value extends boolean-
ValueType-
FallbackTypenull

Example​

declare function get<const Required extends boolean = false>(
  required?: Required
): If<Required, string>;

const a = get(true);
//    ^? string

const b = get(false);
//    ^? string | null

declare const someBoolean: boolean;
const c = get(someBoolean);
//    ^? string | null