betterr

A better way to handle errors

Advantages

Unlike with try...catch or promises:

• Both data and errors are declared with const, available at the top level, and non-nullable (once the other is handled)
• Errors are always Error objects

Installation

$ npm install betterr

Usage

1. Wrap any code that may throw

import { betterr } from 'betterr'; // const { betterr } = require('betterr');

const { data: user, err } = await betterr(() => getUserWithId(1));
// user: User | null, err: Error | null

2. Now either

• Avoid handling the error, and use optional chaining

  const maybeName = user?.name; // maybeName: string | undefined

• Handle the error (interrupting the control flow), after which optional chaining is not needed

  if (err) return; // user: User (after error handled)
  const name = user.name; // name: string

Explanation

betterr / betterSync execute a callback and return an object with data (callback return value) and err (error during execution), one of which will be null depending on the success of the callback.

• betterr can be used with both asynchronous and synchronous callbacks.

• betterrSync can only be used with synchronous callbacks, but avoids wrapping the data in a promise so that await is not necessary.

TypeScript

Both betterr and betterrSync are generic.

• The callback return type must be assignable to the first generic parameter (for data). It defaults to the callback return type.
• The second generic parameter (for err) must extend the Error object. It defaults to Error.

/**
 * const betterrSync: <TData, TError extends Error = Error>
 * (callback: () => TData) =>
 * | { data: TData; err: null }
 * | { data: null; err: TError }
 */

const { data, err } = betterrSync<User, RangeError>(() => ({ id: 1 }));
// data: User | null, err: RangeError | null