30-seconds-of-code/snippets/toHash.md

title, tags, expertise, cover, firstSeen, lastUpdated

title	tags	expertise	cover	firstSeen	lastUpdated
Iterable to hash	array	intermediate	blog_images/sleepy-cat.jpg	2018-05-31T02:14:04+03:00	2022-01-30T12:45:30+03:00

Reduces a given iterable into a value hash (keyed data store).

• Use Object.values() to get the values of the iterable (object or array).
• Use Array.prototype.reduce() to iterate over the values and create an object, keyed by the reference value.

const toHash = (object, key) =>
  Object.values(object).reduce((acc, data, index) => {
    acc[!key ? index : data[key]] = data;
    return acc;
  }, {});

toHash([4, 3, 2, 1]); // { 0: 4, 1: 3, 2: 2, 3: 1 }
toHash([{ a: 'label' }], 'a'); // { label: { a: 'label' } }