pickBy

Creates a new object containing only the entries for which the predicate returns truthy. The predicate receives (value, key) for each own enumerable string property.

Try it

Import

import { pickBy } from "1o1-utils";

import { pickBy } from "1o1-utils/pick-by";

Signature

function pickBy<T extends Record<string, unknown>>({
  obj,
  predicate,
}: PickByParams<T>): Partial<T>

Parameters

Name	Type	Required	Description
obj	Record<string, unknown>	Yes	The source object
predicate	(value, key) => boolean	Yes	Called per entry; the entry is kept when the function returns truthy

Returns

Partial<T> — A new object with only the entries the predicate kept.

Examples

pickBy({ obj: { a: 1, b: null, c: 3 }, predicate: (v) => v !== null });
// => { a: 1, c: 3 }

pickBy({
  obj: { name: "Ada", email: "", phone: "1234" },
  predicate: (v) => typeof v === "string" && v.length > 0,
});
// => { name: "Ada", phone: "1234" }

Edge Cases

• Throws if obj is not an object or is null.
• Throws if predicate is not a function.
• Prototype-pollution keys (__proto__, constructor, prototype) are skipped.
• Inherited keys are ignored — only own enumerable string keys are visited.

Also known as

filter object, conditional pick, object filter, predicate pick

Prompt suggestion

I'm using 1o1-utils (npm: https://www.npmjs.com/package/1o1-utils, GitHub: https://github.com/pedrotroccoli/1o1-utils, LLM context: https://pedrotroccoli.github.io/1o1-utils/llms.txt). Show me how to use pickBy to drop nullable fields from an API response before saving to state.