# Handling Asynchronous Errors in Express with `express-async-errors`

When working with Express.js, handling errors in asynchronous functions can be a bit tricky. Express's default error handling mechanism does not catch exceptions thrown in asynchronous code (e.g., using `async/await`). This is where the `express-async-errors` library comes to the rescue. It simplifies error handling in asynchronous routes by allowing you to leverage the global error-handling middleware without needing to manually add `try-catch` blocks in every async function.

## Installation

You can install the `express-async-errors` library using npm:

```bash
npm install express-async-errors
```

## How to Use

To use this library, simply import it at the top of your main file (e.g., `server.js`) before declaring your routes. This library automatically modifies Express's behavior to catch asynchronous errors and pass them to the error-handling middleware.

## Example Code

### Without `express-async-errors`

Without `express-async-errors`, you need to manually handle errors in each asynchronous function using `try-catch` blocks:

```javascript
import express from "express";
import mongoose from "mongoose";
import dotenv from "dotenv";

dotenv.config();

const app = express();

app.use(express.json());

app.get("/", (req, res) => {
  res.send("Hello, SSO!");
});

app.get("/async-route", async (req, res, next) => {
  try {
    const data = await someAsyncFunction();
    res.send(data);
  } catch (err) {
    next(err); // Pass the error to the error-handling middleware
  }
});

app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send("Something broke!");
});

const port = process.env.PORT || 5100;
app.listen(port, () => {
  console.log(`Server is running on port ${port}`);
});
```

### With `express-async-errors`

When using `express-async-errors`, you no longer need to manually add `try-catch` blocks in each async function. The library automatically catches these errors and passes them to the error-handling middleware:

```javascript
import express from "express";
import mongoose from "mongoose";
import dotenv from "dotenv";
import "express-async-errors"; // Import the express-async-errors library

dotenv.config();

const app = express();

app.use(express.json());

app.get("/", (req, res) => {
  res.send("Hello, SSO!");
});

app.get("/async-route", async (req, res) => {
  const data = await someAsyncFunction();
  res.send(data);
});

// Global error-handling middleware
app.use((err, req, res, next) => {
  console.error(err.stack);
  res.status(500).send("Something broke!");
});

const port = process.env.PORT || 5100;
app.listen(port, () => {
  console.log(`Server is running on port ${port}`);
});
```

By incorporating `express-async-errors`, you can simplify your code and make it cleaner and easier to maintain. It allows you to focus on the core functionality of your application rather than error handling in every async route.

Simplify Express.js async error handling with express-async-errors.

NodeJS

Handling Asynchronous Errors in Express with "express-async-errors"