tsafe

What is tsafe?

The tsafe package provides utility functions for TypeScript that help ensure type safety and improve type inference. It includes functions for exhaustive type checks, type assertions, and more.

What are tsafe's main functionalities?

exhaustiveSwitch

The exhaustiveSwitch function is used to ensure that all possible cases in a switch statement are handled. If a case is not handled, it throws an error, helping developers catch missing cases at compile time.

function exhaustiveSwitch(value: never): never { throw new Error(`Unhandled case: ${value}`); }

assert

The assert function is used to assert that a condition is true. If the condition is false, it throws an error. This is useful for runtime checks that also inform TypeScript's type system.

function assert(condition: any, msg?: string): asserts condition { if (!condition) { throw new Error(msg); } }

Other packages similar to tsafe

ts-essentials

The ts-essentials package provides a set of essential utilities for TypeScript, including advanced types and type guards. It offers more comprehensive utilities compared to tsafe, focusing on enhancing TypeScript's type system capabilities.

type-fest

Type-fest is a collection of essential TypeScript types. It provides a wide range of utility types that extend TypeScript's built-in types, offering more flexibility and power. While tsafe focuses on runtime type safety, type-fest is more about enhancing type definitions.

README

A collection of utilities to take your TypeScript development up a notch

Home - Documentation

Three GIFs to convince you that you need tsafe in your life

Assert things you know are true, get runtime errors where you were wrong:

Implement compile time unit testing (example):

Make TypeScript believe whatever you say:

Motivations

Powerful TypeScript features like assertion functions or user-defined type guards are only useful if paired with utility functions.

TypeScript, however, only exports type helpers (e.g. Record, ReturnType, etc.).

This module provides «the missing builtins» such as the assert function and corrects frustrating aspects of default utility types such as ReturnType.

Documentation website

Installation

tsafe is both an NPM and a Deno module. (Achieved with denoify)

Import in deno:

import { assert, typeGuard, ... } from "https://deno.land/x/tsafe/mod.ts";

Install elsewhere:

$ npm install --save tsafe
#OR
$ yarn add tsafe