Sequence NODE_254

Easy

Handle 404 Not Found for Unknown Routes

Express.js

Node.js

Technical Specification

Add a catch-all middleware that returns a JSON 404 error for unknown routes.

Input/Output Samples

Input:GET /unknown

Output:404 { error: 'Not found' }

Optimal Logic Path

app.use((req, res) => {
  res.status(404).json({ error: "Not found" });
});

Architectural Deep-Dive

A final middleware without a path parameter will match any request not handled earlier.