Express REST API

1. Name 3 real world use cases where you’d want to change the request with custom middleware
   • printing a message
   • trigger an error handler
   • request timestamp

2. True or false: The route handler is middleware?

   • false, a middleware function requires next argument to proceed to next

3. In what ways can a middleware function end the process and send data to the browser?

   • response.end()
   • response.status(number).send('message')

4. At what point in the request lifecycle can you “inject” middleware?

   • after HTTP method and before the Path

5. What can cause express to error with “Request headers sent twice, cannot start a second response”

   • callback has been called twice
   • another function trying to set a header or status code

Terms

• Middleware: functions that that execute during the lifecycle of a request to the Express server

• Request Object: the main entry point for an application to issue a request to the Library

• Response Object: send data from the server to the client through an HTTP request

• Application Middleware: send requests to the server

• Routing Middleware: bound to an instance of express.Router()

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