Utility types and helper for deeply omitting a field from an object

deep-omit.ts

type DeepKeyof<T, A = never> = { [P in keyof T]: T[P] extends object ? P extends A ? P : DeepKeyof<T[P], A | keyof T> | P : P }[keyof T];

type DeepOmit<T, U extends DeepKeyof<T>> = {
    [P in keyof T as P extends U ? never : P]: T[P] extends object ?
    keyof DeepOmit<T[P], Extract<U, DeepKeyof<T[P]>>> extends never ?
    {} :
    DeepOmit<T[P], Extract<U, DeepKeyof<T[P]>>> :
    T[P]
};

/**
 * @summary deep omits a property from an object
 * @param obj object to omit from
 * @param key name of the property to omit
 * @returns a copy of the object without the key
 */
const deepOmit = <T, U extends DeepKeyof<T>>(obj: T, key: U) => {
    const filtered = {} as DeepOmit<T, U>;

    Object.entries(obj).forEach(([k, v]) => {
        if (k === key) return;

        filtered[k as keyof DeepOmit<T, U>] = typeof v === "object" ?
            deepOmit(v as T[keyof T], key as Extract<U, DeepKeyof<keyof T>>) :
            v;
    });

    return filtered;
};