@fenge/types

A type replacement for enhancing TypeScript built-in apis.

What is it

TypeScript supports replacing built-in definitions by installing a lib to node_modules, since v4.5. TypeScript built-in definitions have a large number of any, which are not type-safe enough.

This is a library that provides stricter type definitions for enhancing TypeScript built-in apis.

Features

Here are all features and differences between the built-in definitions and this library.

Without this library:

• 🚨 JSON.parse returns any.
• 🚨 Array.isArray returns any[].
• 🚨 new Map() generates Map<any, any>.
• 🚨 new Promise() can reject a non Error variable.
• 🚨 Promise.reject accepts any as a reason.
• 🚨 Promise.prototype.catch accepts (reason: any) => void | PromiseLike<void>.
• 🚨 Promise.prototype.then accepts (reason: any) => void | PromiseLike<void> for the second parameter.

With this library:

• 👍 JSON.parse returns unknown.
• 👍 Array.isArray returns unknown[].
• 👍 new Map() generates Map<unknown, unknown>.
• 👍 new Promise() must reject an Error variable.
• 👍 Promise.reject accepts Error as a reason.
• 👍 Promise.prototype.catch accepts (reason: unknown) => void | PromiseLike<void>.
• 👍 Promise.prototype.then accepts (reason: unknown) => void | PromiseLike<void> for the second parameter.

Usage

Firstly, if you have install @types/node, make sure its version >= 18.0.0.

Then, add this library to devDependencies field in package.json file. You can replace the version of 0.4.0 with the expected version.

1{
2  "devDependencies": {
3    "@typescript/lib-es2020": "npm:@fenge/types@0.4.0"
4  }
5}

Finally, run npm install or yarn install or pnpm install.

After that, writing TypeScript code will be more type-safe. Example:

1const foo = JSON.parse('{"bar": 1}'); // The `foo` is `unknown` type now.
2console.log(foo.baz + 1); // error: 'foo' is of type 'unknown'.

License

MIT