Functionutilsv0.6.1

hasKeys

Checks for the presence of nested keys in an object that's possibly a distributed union, narrowing the object type accordingly.

Checks if an object has the specified nested keys and that their values are not null or undefined. If they are not, the object type is narrowed to reflect the presence of these keys with their respective types from the original distributed union object.

hasKeys<Obj, Keys>(
    obj: Obj,
    keys: Keys[]
): obj is Obj &
    UnionToIntersection<
        Keys extends unknown
            ? PathToObj<
                  Keys,
                  UnionToIntersection<
                      NonNullable<DeepGet<Obj, Keys>>
                  >
              >
            : never
    >

hasKeys<Obj, Keys>(
    obj: Obj,
    keys: Keys[]
): obj is Obj &
    UnionToIntersection<
        Keys extends unknown
            ? PathToObj<
                  Keys,
                  UnionToIntersection<
                      NonNullable<DeepGet<Obj, Keys>>
                  >
              >
            : never
    >

interface Test {
  a?: {
    b?: {
      c?: string;
    };
  } | null;
  x?: number | null;
}

const obj: Test = { a: { b: { c: 'hello' } }, x: 42 };

if (hasKeys(obj, ['a.b.c', 'x'])) {
  // Here, obj is narrowed to:
  // {
  //   a: { b: { c: string } };
  //   x: number;
  // }
  console.log(obj.a.b.c.toUpperCase()); // Safe to access and use
  console.log(obj.x.toFixed(2)); // Safe to access and use
}

interface Test {
  a?: {
    b?: {
      c?: string;
    };
  } | null;
  x?: number | null;
}

const obj: Test = { a: { b: { c: 'hello' } }, x: 42 };

if (hasKeys(obj, ['a.b.c', 'x'])) {
  // Here, obj is narrowed to:
  // {
  //   a: { b: { c: string } };
  //   x: number;
  // }
  console.log(obj.a.b.c.toUpperCase()); // Safe to access and use
  console.log(obj.x.toFixed(2)); // Safe to access and use
}

Obj

Obj

Obj

Keys

Keys

Keys

obj

obj: Obj

obj: Obj

The object to check.

keys

keys: Keys[]

keys: Keys[]

An array of dot-notation paths to check.