Features

• 🎯 High-quality module design
• ⚡ Lightweight sub-package exports
• 📦 Tree-shakeable ES modules
• ✅ Zero dependencies

Installation

npm install @peerigon/typescript-toolkit --save

Also available on JSR.

Usage

Import only the utilities you need. Each one is exposed as its own subpath:

import { assert } from "@peerigon/typescript-toolkit/assert";

Utilities

| Module | Description | Docs | | ---------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------- | --------------------------------------------------- | | api | Define a typed JSON API client with an overridable hook pipeline | → | | api/rate-limit | Rate-limited fetch for defineApi (pacing + Retry-After) | → | | api/result | defineApiResult — like defineApi, but returns Result.Sync | → | | assert | Assert a value is not null or undefined, with TypeScript narrowing | → | | assert-never | Assert a code path is unreachable, for exhaustive switch/case statements | → | | concurrency/once | Run an async function at most once (single-flight + cache) | → | | concurrency/once/result | once with a synchronous Result snapshot | → | | concurrency/exactlyOnce | Invoke an async function exactly once; second call throws | → | | concurrency/exactlyOnce/result | exactlyOnce with a synchronous Result snapshot | → | | concurrency/mutex | Serialize async tasks (concurrency 1) | → | | concurrency/rate-limit | Pace async task starts (max per sliding interval) | → | | need | Assert a value is not null or undefined and return it with a narrowed type | → | | no-null | Convert between null and undefined in JSON-like values (runtime + types) | → | | dedupe | Remove duplicate values from an array while preserving first-occurrence order | → | | emitter | Minimal typed event emitter with payload objects per event | → | | enums | Lightweight string-enum alternative for erasableSyntaxOnly TypeScript projects | → | | map-leaves | Deeply map leaves in JSON-like values (mutates arrays/objects in place) | → | | match | Exhaustive pattern matching with compile-time case checks, similar to switch | → | | metadata | Typed metadata attached to objects via per-channel WeakMap stores | → | | namespace | Hierarchical namespaces with exclusive member claims and dotted prefixes | → | | result | Type-safe error handling with pending, success, and error states | → | | runtime | Generator-based runtime for the generator context pattern, with type-safe yield* | → | | signals | Push-based reactive state with explicit watchers and signal.from adapters | → | | sleep | Promise-based delay with optional AbortSignal cancellation | → | | stable-stringify | Deterministic stringify for JSON + Map/Set/BigInt/Symbol/Date/RegExp | → | | stable-stringify/json | JSON-only deterministic JSON.stringify with sorted object keys | → | | unwrap | Extract values from Result or nullable types, with optional fallback support | → |

License

MIT

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