pickBy

Creates an object composed of the properties the given function returns truthy 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 falsy value. Use Array.prototype.reduce() to convert the filtered keys back to an object with the corresponding key-value pairs.

typescript

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

typescript

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