Proposal: `RecordOf`

[stabai]

Short summary

Given:

• TupleType: a tuple of similar objects
• KeyProperty: a key that is...
  • Present on every object in the tuple
  • Used to hold string values

Provide: A Record-like object that indexes the tuple entries using the specified key property instead of array indexes.

Potential definition

Type:

type RecordOf<
  TupleType extends Array<object> | ReadonlyArray<object>,
  KeyProperty extends keyof TupleType[number]
> = {
  [Item in TupleType[number] as `${Item[KeyProperty]}`]: Item;
};

Transformation function:

function toRecord<
  TupleType extends Array<object> | ReadonlyArray<object>,
  KeyProperty extends keyof TupleType[number]
>(
  tuple: TupleType,
  keyProperty: KeyProperty
): RecordOf<TupleType, KeyProperty> {
  return Object.fromEntries(
    tuple.map((item: TupleType[number]) => [String(item[keyProperty]), item])
  ) as RecordOf<TupleType, KeyProperty>;
}

Example usage

const animalList = [
  { name: 'Shadow', species: 'dog', breed: 'Golden Retriever' },
  { name: 'Chance', species: 'dog', breed: 'Bulldog' },
  { name: 'Sassy', species: 'cat', breed: 'Siamese' },
  { name: 'Jake the Dog', species: 'dog', breed: 'Bulldog', isMagical: true },
] as const;

const animals = toRecord(animalList, 'name');

console.log(animals.Shadow);
console.log(animals['Jake the Dog'].isMagical);

Playground

Other potential variations

• Provide transformation options (like camel casing the keys or adding a prefix)

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