@jonmumm/utils

A collection of TypeScript utilities.

Installation

npm install @jonmumm/utils

API Documentation

catchError

A typed error handling utility that returns a tuple of [error, data]. This pattern helps avoid try/catch blocks and provides better type safety.

Signature

function catchError<T, E extends Error = Error>(
  promise: Promise<T>,
  errorsToCatch?: Array<new (...args: unknown[]) => E>
): Promise<[E | undefined, T | undefined]>;

Parameters

• promise: The promise to handle
• errorsToCatch (optional): Array of error classes to catch. If not provided, catches all errors.

Returns

Promise resolving to a tuple:

• First element: The caught error (if any) or undefined
• Second element: The successful data (if any) or undefined

Usage Examples

Basic Usage

import { catchError } from "@jonmumm/utils/catchError";

async function example() {
  const [error, user] = await catchError(getUser(123));

  if (error) {
    console.log("There was an error", error.message);
    return;
  }

  // TypeScript knows user is defined here
  console.log(user);
}

Catching Specific Errors

import { catchError } from "@jonmumm/utils/catchError";

class NotFoundError extends Error {}
class ValidationError extends Error {}

async function example() {
  const [error, user] = await catchError(getUser(123), [
    NotFoundError,
    ValidationError
  ]);

  if (error) {
    if (error instanceof NotFoundError) {
      console.error("User not found");
    } else {
      console.error("Invalid user ID");
    }
    return;
  }

  // TypeScript knows user is defined here
  console.log(user);
}

Note: Other errors not specified in the errorsToCatch array will be thrown normally.