objectively

Tiny, dependency-free, strongly-typed object helpers.

Standard Object.* methods widen keys to string and values to their union. These wrappers keep the object's own key/value types, and add transform helpers that let you name the exact output shape — so the one unavoidable assertion lives here, and your call sites stay cast-free.

Exact-keys assumption. The precise types are produced by an internal as: they assert the object holds no keys beyond those in its type. Safe for literals built in place; a lie for objects that arrive with extra keys.

Install

pnpm add objectively

API

Access — keys · values · entries

Typed Object.keys / Object.values / Object.entries.

import { entries } from "objectively";

for (const [key, value] of entries({ a: 1, b: "x" })) {
  // key: "a" | "b",  value: number | string
}

Fold — reduce

Object-shaped reduce; each key and value carries its own type.

reduce({ a: 1, b: 2 }, (acc, key, value) => acc + value, 0); // 3

Transform values — map · remap

map maps every value, preserving keys. remap<Source, Result> rebuilds into a named result shape whose value type may vary per key.

map({ a: 1, b: 2 }, (v) => v * 10); // { a: 10, b: 20 }

Transform keys — rekey

rekey<Source, Result> transforms each entry into a new [key, value] pair, so the key may change too — prefixing or renaming, landing on a named result shape without a cast at the call site.

import { rekey } from "objectively";

// { variant: "solid" } -> { "data-variant": "solid" }
rekey<Props, Bindings>(props, (key, value) => [`data-${key}`, value]);

Guards — record · object · equals

record narrows to a plain record (prototype is Object.prototype or null), object to any non-array object (class instances included), and equals is deep structural equality (SameValueZero, so NaN equals itself).

import { equals, object, record } from "objectively";

record({ a: 1 }); // true    record([]) / record(new Date()); // false
object(new Date()); // true  object([]); // false
equals({ a: [1, NaN] }, { a: [1, NaN] }); // true

Scripts

• pnpm build — bundle to .dist via unbuild
• pnpm test — run the vitest suite
• pnpm typecheck — tsc --noEmit
• pnpm lint — eslint