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2 questions
What happens during an Express request?
Express handles requests through a sequence of registered middleware and route handlers. Middleware can inspect or change the request, stop it with a response, or pass it onward. The order of registration matters because later handlers see the result of earlier ones.
How should Express handle errors?
Error handling turns application failures into predictable responses and useful internal logs. Express uses error middleware with four arguments to handle errors passed into its request pipeline. Synchronous throws are handled by Express, while promise forwarding differs between Express 4 and 5.
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