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FunctionKeys<T> #29

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nmsn opened this issue Apr 1, 2023 · 1 comment

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nmsn commented Apr 1, 2023

/**
 * FunctionKeys
 * @desc Get union type of keys that are functions in object type `T`
 * @example
 *  type MixedProps = {name: string; setName: (name: string) => void; someKeys?: string; someFn?: (...args: any) => any;};
 *
 *   // Expect: "setName | someFn"
 *   type Keys = FunctionKeys<MixedProps>;
 */

nmsn added the utility-types label

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nmsn commented Apr 1, 2023

export type FunctionKeys<T extends object> = {
  [K in keyof T]-?: NonUndefined<T[K]> extends Function ? K : never;
}[keyof T];

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