TypeScript utility type to pick deep keys of an object

deepObjectKeys.ts

type DeepObjectKeys<T> = T extends Record<string, unknown>
  ? {
      [K in keyof T]-?: K extends string ? `${K}` | `${K}.${DeepObjectKeys<T[K]>}` : never
    }[keyof T]
  : never

const testObj = {
  foo: {
    bar: false,
    baz: {
      ban: 123,
    },
  },
  awd: [true, false],
}

const _deepKey: DeepObjectKeys<typeof testObj> = 'foo.baz.ban'