Errly

Error handling in JavaScript is done using try...catch blocks, which can get messy and verbose very quickly. Errly makes the error handling experience similar to that of Golang.

Features

• Zero dependencies. Small bundle size.
• Written in TypeScript.
• Seamless support for synchronous & asynchronous functions.
• Modern ESModules support.

Usage

Consider the following function:

const throwIfEven = (num: number) => {
    if (!(num % 2)) throw new Error("It's even!");
    return num;
};

Here's how you would normally handle errors from calls to throwIfEven:

function main() {
    try {
        // Happy path:
        const data = throwIfEven(6);
        console.log(data);
        // ...
    } catch (error) {
        // Sad path:
        console.log((error as Error).message);
        return;
    }
}

One issue here is that data is now scoped to the try block, and cannot be used outside of it. Same goes for error being scoped to the catch block. Here's how the same piece of logic looks when using Errly to handle the error:

import { e } from 'errly';

function main() {
    // Scoped to the function.
    const [data, err] = e(() => throwIfEven(6));
    // Write error handling logic first.
    if (err !== null) {
        // Sad path:
        console.log(err.message);
        return;
    }
    // Happy path:

    // TypeScript will understand that "data" is
    // definitely a number and can't be null because
    // the error path was handled above.
    console.log(data);
    // ...
}

With async code

Usage with async functions is the same as above with only the addition of the await keyword.

const doStuff = async () => {
    // Wait for two seconds
    await new Promise((r) => setTimeout(r, 2e3));
    throw new Error('foo');
};

const [_, err] = await e(() => doStuff());
if (err !== null) {
    // Handle error
}

Creating new functions

If using e() all the time doesn't seem like your style, you can instead convert regular functions into Errly functions by using func().

import { func } from 'errly';

const add = func((n1: number, n2: number) => {
    const sum = n1 + n2;
    if (sum > 100) {
        throw new Error('Sum is massive!');
    }

    return sum;
});

const [sum, err] = add(1337, 420);
if (err !== null) {
    // Handle error
}