An alternative TypeScript standard library with better type definitions.

See the v2 branch for 2.0.0 that supports TypeScript 4.5.

While it is well known that TypeScript is not very type safe due to the existence of any and other pitfalls, TypeScript's built-in type definitions are also to blame for that unsafety. For example, it is handy but very unsafe that the return type of JSON.parse is any.

The core type checker of TypeScript has been improved to be more type safe, maintaining backwards compatibility through compiler options. Unfortunately, however, the type definitions are still not very good, and are harder to improve keeping backwards compatibility.

This package provides an alternative set of type definitions which replaces, and is safer than TypeScript's built-in ones. With this package, TypeScript users obtain less chance of unexpectedly getting any values. For example, in this type definition the return type of JSON.parse is not any, but JSONData which represents all possible JSON data.

This package also includes other improved, stricter type definitions.

npm i -D better-typescript-lib

- "lib": ["es5", "dom"]
+ "noLib": true

Include better-typescript-lib with triple-slash directives from the entry point of your code. Note that these directives must be placed at the very top of a .ts file.

/// <reference path="./node_modules/better-typescript-lib/lib.es5.d.ts" />
/// <reference path="./node_modules/better-typescript-lib/lib.dom.d.ts" />

Better-typescript-lib is not meant to be compatible with TypeScript's built-in library. Therefore it is the most suitable to new TypeScript projects. An existing project may also adopt better-typescript-lib but additional type errors need to be fixed.

As this is only an alternative to TypeScript's built-in type definitions, we have no plan of providing any runtime implemention through better-typescript-lib.

Improvements to type definitions may be released as a new minor version even if it may cause new type errors to existing codebases.

Welcome

This work is based on TypeScript's standard library created by Microsoft Corporation. We modify it as programmed in this repository and redistribute it under Apache 2.0 License.