title: omitBy tags: object,array,function,intermediate

Creates an object composed of the properties the given function returns falsy for. The function is invoked with two arguments: (value, key).

Use Object.keys(obj) 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.

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

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