When a client sends a request to an Express.js server with JSON data, the express.json() middleware comes into play. Here’s how the flow of data works in this case:
1.The client sends a request to the server with JSON data in the request body.
2.The Express.js server receives the request and passes it to the express.json() middleware.
3.The express.json() middleware reads the request body and parses it as JSON.
4.The parsed JSON data is then stored in the req.body property of the request object.
5.The request then moves on to the next middleware in the middleware chain, or to the relevant route handler, depending on the configuration of your Express.js application.
In the route handler, you can access the parsed JSON data by using req.body. For example, you could access individual properties of the JSON object like this: req.body.propertyName.
Finally, the route handler returns a response to the client, which typically includes information generated from the parsed JSON data.
In summary, the express.json() middleware parses incoming request data as JSON, makes it available as a JavaScript object in the req.body property, and makes it easy for the route handler to access and use the data.
