ts-gems/lib/omit-undefined.d.ts

Valuable typing extensions for TypeScript

import { IfNoDeepValue } from './helpers.js';
import { IfNever } from './type-check.js';

/**
 * OmitUndefined<T> is a type that omits all properties with a value of type "undefined".
 */
export type OmitUndefined<T> = {
  [K in keyof T as IfNever<Exclude<T[K], undefined>, never, K>]: T[K];
};

/**
 * Omit all "never" and "undefined" properties in T deeply
 */
export type DeepOmitUndefined<T> = {
  [K in keyof T as IfNever<Exclude<T[K], undefined>, never, K>]: IfNoDeepValue<
    // Do not deep process No-Deep values
    Exclude<T[K], undefined>
  > extends true
    ? T[K]
    : // Deep process objects
      DeepOmitUndefined<Exclude<T[K], undefined>>;
};

/**
 * Omit all "never" and "undefined" properties in T deeply including arrays
 */
export type DeeperOmitUndefined<T> = {
  [K in keyof T as IfNever<Exclude<T[K], undefined>, never, K>]: NonNullable<
    T[K]
  > extends (infer U)[] // Deep process arrays
    ? DeeperOmitUndefined<U>[]
    : // Do not deep process No-Deep values
      IfNoDeepValue<NonNullable<T[K]>> extends true
      ? T[K]
      : // Deep process objects
        DeeperOmitUndefined<NonNullable<T[K]>>;
};