Async Handler

A lightweight utility for handling async errors in Express.js.

Async Handler

A lightweight utility for handling async/await errors in Express.js route handlers without using repetitive try/catch blocks.

It automatically catches rejected promises and forwards errors to Express error middleware.

Why Use This?

In Express applications, async routes often require repetitive error handling like this:

app.get("/users", async (req, res, next) => { try { const users = await User.find(); res.json(users); } catch (error) { next(error); } })

With async-handler, you can write cleaner code:

app.get( "/users", asyncHandler(async (req, res) => { const users = await User.find(); res.json(users); }) )

Installation

npm install express-async-handler

Usage

Import the handler and wrap your async route functions.

const asyncHandler = require("express-async-handler");

Example

const express = require("express"); const asyncHandler = require("express-async-handler");

const app = express();

app.get( "/users", asyncHandler(async (req, res) => { const users = await User.find(); res.json(users); }) )

If an error occurs, it will automatically be passed to Express error middleware.

How It Works

The utility wraps an async function and ensures that rejected promises are passed to Express's next() function.

Implementation:

const asyncHandler = (fn) => (req, res, next) => { Promise.resolve(fn(req, res, next)).catch(next); };

module.exports = asyncHandler;

Error Middleware Example

Make sure your Express app has an error handler.

app.use((err, req, res, next) => { res.status(500).json({ message: err.message, }) })

Features

1. Removes repetitive try/catch
2. Clean and readable async routes
3. Tiny and lightweight
4. Works with all Express versions supporting async functions

License

MIT