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

title, tags, expertise, cover, firstSeen, lastUpdated

title	tags	expertise	cover	firstSeen	lastUpdated
Filter matching and unspecified values	array	intermediate	blog_images/little-bird.jpg	2017-12-22T09:37:36+02:00	2020-10-22T20:24:04+03:00

Filters an array of objects based on a condition while also filtering out unspecified keys.

• Use Array.prototype.filter() to filter the array based on the predicate fn so that it returns the objects for which the condition returned a truthy value.
• On the filtered array, use Array.prototype.map() to return the new object.
• Use Array.prototype.reduce() to filter out the keys which were not supplied as the keys argument.

const reducedFilter = (data, keys, fn) =>
  data.filter(fn).map(el =>
    keys.reduce((acc, key) => {
      acc[key] = el[key];
      return acc;
    }, {})
  );

const data = [
  {
    id: 1,
    name: 'john',
    age: 24
  },
  {
    id: 2,
    name: 'mike',
    age: 50
  }
];
reducedFilter(data, ['id', 'name'], item => item.age > 24);
// [{ id: 2, name: 'mike'}]