data-path

Type-safe object property paths in TypeScript — build, compare, and manipulate with lambda expressions. Zero dependencies.

Documentation: https://sergeyshmakov.github.io/data-path/

Before / after

// Before — string literals, invisible to the compiler
register("users.0.profile.firstName");
table.getColumn("contact.email");
set(state => ({ ...state, settings: { ...state.settings, theme } }));

// After — typed, IDE-autocompleted, refactor-safe
register(path((u: FormData) => u.users[0].profile.firstName).$);
table.getColumn(emailPath.$);
set(state => themePath.set(state, theme));

What it is

A zero-dependency TypeScript library that captures object property paths via proxy-based lambdas. Build a path once — use it as a string, read and write data through it, compose paths together, or match one against another.

• Typed root to leaf — renaming a property breaks the path at compile time
• Safe get, immutable set, read-modify-write update
• Template paths (each, deep) for bulk operations across collections and trees
• Path algebra: merge, subtract, slice, to
• Runtime indices and closure variables work natively inside lambdas

Install

npm install data-path

Requirements: Node >=20, TypeScript >=5.0

Quick start

import { path } from "data-path";

type User = { profile: { firstName: string; lastName: string }; tags: string[] };

const firstNamePath = path((u: User) => u.profile.firstName);

firstNamePath.$                        // "profile.firstName"
firstNamePath.get(user)                // "Alice" | undefined
firstNamePath.set(user, "Bob")         // returns a new User — original unchanged
firstNamePath.fn                       // stable (u: User) => string | undefined

Works well with

| Package | How it helps | |---------|--------------| | React Hook Form | Type-safe field names for register, watch, setValue | | TanStack Form | Typed field names with runtime index support | | TanStack Table | Typed column accessors — no manual id strings | | Zustand | Immutable nested state updates without Immer | | Zod | Map ZodError.issues paths to specific form fields | | React useState | Structural clones for deeply nested state |

Guides

• Data access — get, set, update, fn
• Templates — each, deep, bulk writes across collections
• Path algebra — merge, subtract, slice, to
• Relational — startsWith, covers, match
• Runtime variables — dynamic indices and closures

AI tooling

This package is available in Context7 and documented in a Cubic wiki. An Agent Skills-compatible skill is included:

npx ctx7 skills install /sergeyshmakov/data-path data-path

Contributing

See CONTRIBUTING.md.

License

MIT License