[Solved] In Express.js, which function signature correctly defines a centralized error handling middleware? — Ans: (err, req, res, next) => { /* handle error */ } | Node.js

Node.js - Error Handling Patterns

In Express.js, which function signature correctly defines a centralized error handling middleware?

A(err, req, res) => { /* handle error */ }

B(req, res, next) => { /* handle error */ }

C(req, res) => { /* handle error */ }

D(err, req, res, next) => { /* handle error */ }

Step-by-Step Solution

Solution:

Step 1: Understand middleware signatures
Express error handlers must have four parameters: err, req, res, next.
Step 2: Identify correct signature
Only (err, req, res, next) => { /* handle error */ } has all four parameters in the correct order.
Final Answer:
(err, req, res, next) => { /* handle error */ } -> Option D
Quick Check:
Four parameters required for error middleware [OK]

Quick Trick: Error middleware always has 4 parameters (err, req, res, next) [OK]

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In Express.js, which function signature correctly defines a centralized error handling middleware?