@open-xchange/tsconfig

This package exports base configurations for the TypeScript compiler that tsconfig.json files in projects can extend from. All configuration files contain:

• Strict options for type checking (except exactOptionalPropertyTypes, noPropertyAccessFromIndexSignature, and noUncheckedIndexedAccess which are too heavy to satisfy).
• Modern target (es2024) and module settings (esnext and bundler).
• Option skipLibCheck to skip linting external packages for better performance (and too many existing type issues in various packages).

Installation

npm install -D @open-xchange/tsconfig
# or
pnpm add -D @open-xchange/tsconfig
# or
yarn add -D @open-xchange/tsconfig

Usage

Configurations

The following configurations are available:

• @open-xchange/tsconfig/tsconfig.lint.json: For type-checking during lint stage (noEmit set to true).
• @open-xchange/tsconfig/tsconfig.build.json: For building the project (outDir set to "${configDir}/../dist").
• @open-xchange/tsconfig/tsconfig.transform.json: Same as tsconfig.build.json but includes the plugin typescript-transform-paths to transform path aliases. Package must be installed in the project.

Example:

{
  "$schema": "https://json.schemastore.org/tsconfig",
  "extends": "@open-xchange/tsconfig/tsconfig.lint.json",
  "compilerOptions": {
    // custom overrides
  }
}

Lib Type Fixes

All configurations include a few type fixes for TypeScript's built-in type libraries. These type fixes can also be used separately without the configuration presets:

Example:

{
  "$schema": "https://json.schemastore.org/tsconfig",
  "compilerOptions": {
    "types": ["@open-xchange/tsconfig/lib-fixes"]
  }
}

The following type fixes are included:

• Array<T>::filter(Boolean) and ReadonlyArray<T>::filter(Boolean) will narrow T by excluding all falsy types.

  Example:

  const array1 = [1, 2, null, 4].filter(Boolean)
  // resulting type: `number[]` instead of `(number|null)[]`
  
  const array2 = ([1, 2, null, 4] as const).filter(Boolean)
  // resulting type: `(1|2|4)[]` instead of `(1|2|null|4)[]`

• Object.getPrototypeOf(obj) takes an unknown and returns an unknown (instead of anys).

• Object.keys<T>(obj) returns an (keyof T & string)[] instead of string[].

  Example:

  const keys = Object.keys({ a: 1, b: 2, [Symbol.iterator]() {} })
  // resulting type: `('a'|'b')[]` instead of `string[]`

• Object.values<T>(obj) returns an (T[keyof T & string])[] instead of unknown[] or any[].

  Example:

  const values = Object.values({ a: 1, b: 2, [Symbol.iterator]() {} })
  // resulting type: `number[]` instead of `any[]`

• Object.entries<T>(obj) returns an [keyof T & string, T[keyof T & string]][] instead of [string, unknown][] or [string, any][].

  Example:

  const values = Object.entries({ a: 1, b: 2, [Symbol.iterator]() {} })
  // resulting type: `['a'|'b', number][]` instead of `[string, any][]`

• Promise<T>::catch(callback) uses unknown as callback argument instead of any.

  Example:

  Promise.reject().catch(reason => { ... })
  // 'reason' has type `unknown` instead of `any`

• Promise<T>::finally(callback) accepts asynchronous callbacks instead of only VoidFunction.

  Example:

  Promise.reject().finally(async () => { await ... })

• NodeListOf<T>::item(index) returns a T | null instead of a T.