@moonstar-x/tsconfig

Maximally strict, deliberately pedantic TypeScript configurations, built for TypeScript 7.

Three configs: a base carrying every checking rule, plus node and react variants that extend it and add only what their runtime requires.

The premise: every rule here converts a class of runtime bug into a compile error. The configs are opinionated on purpose — if a rule only ever produced noise, it isn't in here.

Install

npm install --save-dev @moonstar-x/tsconfig typescript

typescript >= 6.0.0 is a required peer dependency (the configs use target/lib es2025, which TypeScript 6.0 was the first release to accept). The node variant additionally needs @types/node:

npm install --save-dev @types/node

Usage

Extend the variant you need, then add your own paths. This package intentionally sets no path options (outDir, rootDir, include, exclude, paths, baseUrl).

Node

{
  "extends": "@moonstar-x/tsconfig/node",
  "compilerOptions": {
    "outDir": "./dist",
    "rootDir": "./src"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}

React

{
  "extends": "@moonstar-x/tsconfig/react",
  "compilerOptions": {
    "outDir": "./dist",
    "rootDir": "./src"
  },
  "include": ["src/**/*"],
  "exclude": ["node_modules", "dist"]
}

Base only

For a runtime-agnostic package, or as a starting point for your own variant:

{
  "extends": "@moonstar-x/tsconfig",
  "compilerOptions": { "outDir": "./dist", "rootDir": "./src" },
  "include": ["src/**/*"]
}

Things that will bite you

These are intentional. Each is listed with its escape hatch.

• isolatedDeclarations demands explicit types on exports. export const v = Math.max(1, 2) fails with TS9010; write export const v: number = …. Trivially-inferrable initializers (export const f = () => 1) are still fine. React components need an explicit return type:

export function Counter(props: CounterProps): JSX.Element { … }

Escape hatch: "isolatedDeclarations": false. This is the first flag to drop for an application (as opposed to a published library).

• erasableSyntaxOnly bans enum and namespace. Use a const object plus a union type:

export const Color = { Red: "red", Blue: "blue" } as const;
export type Color = (typeof Color)[keyof typeof Color];

• verbatimModuleSyntax requires import type. A type imported without it is a compile error (TS1484) rather than a silent elision.

• nodenext requires runtime extensions in ESM. In a "type": "module" package, write import { x } from "./x.js" even though the file is x.ts. That's Node's rule, not TypeScript's.

• skipLibCheck: false checks your dependencies' types. This finds real problems, but one broken @types package can block your build. Escape hatch: "skipLibCheck": true.

• exactOptionalPropertyTypes rejects explicit undefined. To allow it, declare it: { a?: string | undefined }.

• noUncheckedIndexedAccess makes every index access possibly-undefined. That is the point. Narrow it, or use .at() and handle the undefined.