await-to-js

What is await-to-js?

The await-to-js npm package is a utility that simplifies error handling in asynchronous JavaScript code. It allows developers to handle errors in a more readable and concise manner by using a tuple pattern with async/await syntax.

What are await-to-js's main functionalities?

Error Handling with Async/Await

This feature allows you to handle errors in asynchronous functions without using try/catch blocks. The `to` function returns a tuple where the first element is the error (if any) and the second element is the resolved value.

const to = require('await-to-js').default;

async function fetchData() {
  const [err, data] = await to(fetch('https://api.example.com/data'));
  if (err) {
    console.error('Error fetching data:', err);
    return;
  }
  console.log('Data:', data);
}

fetchData();

Custom Error Handling

This feature allows you to implement custom error handling logic by checking the error returned in the tuple and passing it to a custom error handler function.

const to = require('await-to-js').default;

async function fetchData() {
  const [err, data] = await to(fetch('https://api.example.com/data'));
  if (err) {
    handleCustomError(err);
    return;
  }
  console.log('Data:', data);
}

function handleCustomError(err) {
  // Custom error handling logic
  console.error('Custom Error Handler:', err);
}

fetchData();

Other packages similar to await-to-js

async-await-error-handling

The async-await-error-handling package provides a similar utility for handling errors in async/await code. It offers a `handle` function that returns a tuple with the error and result, similar to await-to-js. However, it may have a different API and additional features.

await-to

The await-to package is another alternative that provides a `to` function for handling errors in async/await code. It is very similar to await-to-js in terms of functionality and usage, making it a direct competitor.

README

await-to-js

Async await wrapper for easy error handling

Pre-requisites

You need to use Node 7.6 (or later) or an ES7 transpiler in order to use async/await functionality. You can use babel or typescript for that.

Install

npm i await-to-js --save

Usage

import to from 'await-to-js';
// If you use CommonJS (i.e NodeJS environment), it should be:
// const to = require('await-to-js').default;

async function asyncTaskWithCb(cb) {
     let err, user, savedTask, notification;

     [ err, user ] = await to(UserModel.findById(1));
     if(!user) return cb('No user found');

     [ err, savedTask ] = await to(TaskModel({userId: user.id, name: 'Demo Task'}));
     if(err) return cb('Error occurred while saving task');

    if(user.notificationsEnabled) {
       [ err ] = await to(NotificationService.sendNotification(user.id, 'Task Created'));
       if(err) return cb('Error while sending notification');
    }

    if(savedTask.assignedUser.id !== user.id) {
       [ err, notification ] = await to(NotificationService.sendNotification(savedTask.assignedUser.id, 'Task was created for you'));
       if(err) return cb('Error while sending notification');
    }

    cb(null, savedTask);
}

async function asyncFunctionWithThrow() {
  const [err, user] = await to(UserModel.findById(1));
  if (!user) throw new Error('User not found');
  
}

TypeScript usage

interface ServerResponse {
  test: number;
}

const p = Promise.resolve({test: 123});

const [err, data] = await to<ServerResponse>(p);
console.log(data.test);

License

MIT © Dima Grossman && Tomer Barnea