Tree path array

Challenge

Create a type Path that represents validates a possible path of a tree under the form of an array.

Related challenges:

• Object key path

declare const example: {
  foo: {
    bar: {
      a: string;
    };
    baz: {
      b: number;
      c: number;
    };
  };
};

/* Possible solutions: 
[]
['foo']
['foo', 'bar']
['foo', 'bar', 'a']
['foo', 'baz']
['foo', 'baz', 'b']
['foo', 'baz', 'c']
*/

Solution

type Path<T, K extends keyof T = keyof T> = K extends unknown
  ? T[K] extends Record<any, unknown>
    ? [K] | [K, ...Path<T[K]>]
    : [K]
  : never;

References