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

title, tags, cover, firstSeen, lastUpdated

title	tags	cover	firstSeen	lastUpdated
Omit object properties based on function	object	arrow-functions	2018-01-19T13:23:45+02:00	2020-10-21T21:54:53+03:00

Omits the key-value pairs corresponding to the keys of the object for which the given function returns falsy.

• Use Object.keys() and Array.prototype.filter() to remove the keys for which fn returns a truthy value.
• Use Array.prototype.reduce() to convert the filtered keys back to an object with the corresponding key-value pairs.
• The callback function is invoked with two arguments: (value, key).

const omitBy = (obj, fn) =>
  Object.keys(obj)
    .filter(k => !fn(obj[k], k))
    .reduce((acc, key) => ((acc[key] = obj[key]), acc), {});

omitBy({ a: 1, b: '2', c: 3 }, x => typeof x === 'number'); // { b: '2' }