Middleware

1. What is middleware?

Middleware in Express.js are functions that run between receiving a request and sending a response. They can access the request (req), response (res), and a next() function to move to the next middleware.

middleware says - आगे जाने से पहले मुझसे मिलके जाना |

2. How middleware work ?

1. Request comes in:

• A client (like a browser) sends a request to the server.

2. Middleware runs:

Middleware functions process the request

• Modify the request or response objects.
• Log information.
• Perform tasks like authentication or data validation.
• End the request-response cycle by sending a response.
• Pass control to the next middleware using next().

3. Next middleware:

• If next() is called, the next middleware in the stack is executed. If no middleware is left, the final route handler sends the response.

4. Response goes out:

• After all middleware and the route handler have run, the response is sent back to the client.

Example

import express from "express";

const app = express();
const middleware = (req, res, next) => {
  console.log("Your middleware working fine ");

  next();
};

const postOrder = (req, res) => {
  res.json({
    success: true,
    message: "Order placed successfully ",
  });
};

app.post("/order", middleware, postOrder);

app.listen(5005, () => {
  console.log(`Server is running on port 5005`);
});

• A client sends a POST request to /order.
• The middleware function executes:
• Logs "Your middleware working fine" to the console.
• Calls next(), allowing the next handler to run.
• The postOrder function executes Sends a JSON response with the success message.

Happy coding 🤖