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@busypeoples
Last active June 17, 2021 17:14
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Helper Functions in TS
/**
* TS Helper Functions
*/
type ConvertTo<Type, From, To> = {
[Key in keyof Type]: Required<Type>[Key] extends From ? To : Type[Key];
};
type FilterByType<T, U> = {
[Key in keyof Required<T>]: Required<T>[Key] extends U ? Key : never;
}[keyof T];
type ExcludeByType<T, U> = Omit<T, FilterByType<T, U>>;
type IncludeByType<T, U> = Pick<T, FilterByType<T, U>>;
type ReadOnlyByType<T, U> = T & Readonly<IncludeByType<T, U>>;
type OptionalByType<T, U> = Partial<IncludeByType<T, U>> & ExcludeByType<T, U>;
type RequiredByType<T, U> = Partial<ExcludeByType<T, U>> & IncludeByType<T, U>;
type OnlyMakeTypeRequired<T, U> = ExcludeByType<T, U> & Required<IncludeByType<T, U>>;
// Test
type User = {
points: number;
name: string;
active: boolean;
};
/**
type UserOne = {
points: number[];
name: string;
active: boolean;
}
*/
type UserOne = ConvertTo<User, number, number[]>;
/**
type UserTwo = {
name: string;
active: boolean;
}
*/
type UserTwo = ExcludeByType<User, number>;
/**
type UserThree = {
points: number;
}
*/
type UserThree = IncludeByType<User, number>;
/**
type UserFour = {
readonly points: number;
name: string;
active: boolean;
};
*/
type UserFour = ReadOnlyByType<User, number>;
/**
type UserFive = {
points?: number;
name: string;
active: boolean;
};
*/
type UserFive = OptionalByType<User, number>;
/**
type UserSix = {
points: number;
name?: string;
active?: boolean;
};
*/
type UserSix = RequiredByType<User, number>;
/**
type User = {
id: number;
name: string;
points: number;
active?: boolean;
}
*/
type RequiredByTypeOnlyUser = OnlyMakeTypeRequired<{
id: number;
points?: number;
name: string;
active?: boolean;
}, number>;
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