Created
November 5, 2019 23:14
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EnableIf or enable_if in TypeScript
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type EnableIf<T, U, ErrorMessage extends string = never> = T extends true ? U : ErrorMessage; | |
type IsArrayOf<T, U> = T extends U[] ? true : false; | |
function enableIf<T, U>(t: T, u: EnableIf<IsArrayOf<T, U>, U, 'T has to be an array of U'>) { | |
// Code | |
} | |
enableIf([1, 2], 3); | |
enableIf([1, 2], '3'); | |
function enableIf2<T, U>( | |
t: EnableIf<T extends U ? true : false, T, 'T should be a U'>, | |
u: EnableIf<U extends T ? true : false, U, 'U should be a T'>) { | |
// Code | |
} | |
enableIf2(1, 2) | |
enableIf2({}, {t: 0}) | |
enableIf2({t: 0}, {}) | |
enableIf2({t: 0}, {t: 0}) |
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