asynchronous error handling

Demonstration of asynchronous error handling in JavaScript

TL;DR:

• Async operations must be awaited inside a try-catch block to handle errors.
• If it is not awaited, use .catch() to handle errors.
• If neither is done, this will result in an unhandled promise rejection.

Run the Test Cases

Prerequisites

• Node.js
• nvm (optional)

Build

npm install

npm run build

Run

Run the various test cases from VSCode debugger.

Behaviour

Unhandled Promise Rejection

If an async operation is not awaited, and no .catch() is used, it will result in an unhandled promise rejection.

async function unhandledPromiseRejection() {
  Promise.reject(new Error('Unhandled Promise Rejection'));
}

Awaited Promise Rejection

If an async operation is awaited, the error can be caught using a try-catch block.

async function awaitedPromiseRejection() {
  try {
    await Promise.reject(new Error('Awaited Promise Rejection'));
  } catch (error) {
    console.error(error);
  }
}

Catch Promise Rejection

If an async operation is not awaited, but a .catch() is used, the error can be caught.

async function catchPromiseRejection() {
  Promise.reject(new Error('Catch Promise Rejection')).catch((error) => {
    console.error(error);
  });
}