A minimal JavaScript implementation of Rust's Result<T, E> type for expressive and safe error handling.

✨ Features

• Result.Ok(value) and Result.Err(error) constructors
• isOk() / isErr() type guards
• unwrap() / unwrapErr() for accessing values
• map() / mapErr() for transforming results
• No dependencies, fully portable

📦 Installation

npm install @ludeschersoftware/result
# or
yarn add @ludeschersoftware/result

🚀 Usage

import Result from "@ludeschersoftware/result";

const result = parseNumber("42");

if (result.isOk()) {
  console.log("Parsed:", result.unwrap());
} else {
  console.error("Failed:", result.unwrapErr());
}

function parseNumber(str) {
  const num = Number(str);
  return isNaN(num) ? Result.Err("Not a number") : Result.Ok(num);
}

🧠 API

| Method | Description | |----------------|--------------------------------------------------| | Result.Ok(val) | Creates a success result | | Result.Err(err) | Creates an error result | | isOk() | Returns true if result is Ok | | isErr() | Returns true if result is Err | | unwrap() | Returns value if Ok, throws if Err | | unwrapErr() | Returns error if Err, throws if Ok | | map(fn) | Transforms Ok value, passes Err through | | mapErr(fn) | Transforms Err value, passes Ok through |

🧼 License

MIT © Johannes Ludescher

💬 Feedback

Got ideas or improvements? Feel free to open an issue or submit a PR. Contributions are welcome!