Improving TypeScript typings with ts-reset

What is ts-reset ?

ts-reset is an open-source package that provides a set of rules that modify TypeScript's built-in typings. It makes them more strict, more consistent, and more ergonomic. Using ts-reset can help you avoid subtle bugs caused by type errors, and make your code more readable, maintainable and especially more coherent. Think of it as a Typescript version of css-reset.

ts-reset was created by Matt Pocock, who also created Total Typescript, a set of workshops to help you become a "Typescript Wizard". Check it out if you wish to master Typescript, totally worth it!

The problem with Typescript's built-in typings

TypeScript's built-in typings are pretty good, but they're not perfect. They're based on a set of assumptions about how code should work, and those assumptions don't always match reality.

A few examples of the problems you might encounter when working with TypeScript:

• .json (in fetch) and JSON.parse both return any instead of unknown
• .filter(Boolean) doesn't behave how you expect
• array.includes often breaks on readonly arrays

These are just a few examples, but they illustrate the kinds of issues that can crop up when working with TypeScript's built-in typings.

The solution: ts-reset

ts-reset fixes Typescript in a lot of ways. The package provides several rules that you can import globally or individually to make Typescript's built-in typings more strict and coherent. Check out the examples below:

// BEFORE
const result = JSON.parse("{}"); // any

// AFTER ts-reset
const result = JSON.parse("{}"); // unknown

// BEFORE
const filteredArray = [1, 2, undefined].filter(Boolean); // (number | undefined)[]

// AFTER ts-reset
const filteredArray = [1, 2, undefined].filter(Boolean); // number[]

You can find the full list of rules in the package's repository.

How to use ts-reset

Getting started with ts-reset is quite easy:

1. Install the package npm i -D @total-typescript/ts-reset

2. Create a reset.d.ts file in your project with the following code

   import "@total-typescript/ts-reset";
   
   // OR if you wish to include only certain rules, import them individually
   // Makes JSON.parse return unknown
   import "@total-typescript/ts-reset/json-parse";
   
   // Makes await fetch().then(res => res.json()) return unknown
   import "@total-typescript/ts-reset/fetch";
   

3. Have fun with an improved version of Typescript

Keep in mind that you need to set module to NodeNext or Node16 in your tsconfig.json

Don't forget to read the README in the repository: ts-reset is designed to be used in application code, not library code. Meaning that if you include these rules in your library, your users will automatically be using ts-reset rules independently of their will.