In the route handler function below, we are using a try...catch statement for handling errors.
router.get("/courses", async (req, res, next) => {\n try {\n const courses = await Course.find()\n res.send(courses)\n } catch (err) {\n next(err)\n }\n})The problem with this implementation is that we need to repeat the try...catch statement for every route handler.
The solution therefore is to create a middleware function that takes in the route handler and returns an async function with a try...catch statement.
const asyncMiddleware = handler => {\n return async (req, res, next) => {\n try {\n await handler(req, res)\n } catch (err) {\n // Pass the error thrown to the Express error handling middleware\n next(err)\n }\n }\n}Then, we wrap the route handler with the middleware function and the result, as we can see clearly, is a much more concise piece of code without the bloat of a try...catch statement.
router.get(\n "/courses",\n asyncMiddleware(async (req, res) => {\n const courses = await Course.find()\n res.send(courses)\n })\n)Instead of writing our own async handler, we can make use of an npm package called express-async-handler. It is a simple middleware for handling exceptions inside of async express routes and passing them to express error handlers.
npm i express-async-handlerconst asyncHandler = require("express-async-handler")\n\nrouter.get(\n "/courses",\n asyncHandler(async (req, res) => {\n const courses = await Course.find()\n res.send(courses)\n })\n)