record type with exceptional properties

example.ts

// Type and Factory

type RecordX = ReturnType<typeof RecordX>;

function RecordX(
  id: string,
  props?: Record<string, string[]>
) {
  return Object.assign({ id }, props);
}

// USAGE




const model: RecordX = RecordX('id-1', {
  foo: ['a'],
})

// type string
const id = model.id;

// type string[]
const otherProp = model.otherProp;

// string is not assignable to string[]
const model2: RecordX = RecordX('id-2', {
  bar: 'hello'
})