Express res.json() Function

The res.json() function is used to send a JSON response from the Express server to the client. It automatically converts JavaScript objects or arrays into JSON format and sets the Content-Type header to application/json.

Syntax:  

res.json( [body] )

Parameters: The body parameter is the body that is to be sent in the response.

Return Value: Returns the response object (res), allowing method chaining.

Steps to Install the Express Module:

Step 1: You can install this package by using this command.

npm install express

Step 2: After installing the express module, you can check your express version in the command prompt using the command.

npm version express

Project Structure:

Example 1: Below is the code of res.json() Function implementation.

const express = require("express");
const app = express();
const PORT = 3000;
app.get("/user", (req, res) => {
    res.json({
        name: "GeeksforGeeks",
        language: "JavaScript"
    });
});
app.listen(PORT, () => {
    console.log(`Server listening on PORT ${PORT}`);
});

Steps to run the program:

Run the index.js file using the below command: 

node index.js

Console Output: 

Server listening on PORT 3000

Browser Output: Now open the browser and go to http://localhost:3000/user, now on your screen you will see the following output: 

Example 2: Below is the code of res.json() Function implementation.

const express = require('express');
const app = express();
const PORT = 3000;
// Middleware that sends a JSON response
app.use('/', (req, res) => {
    res.json({
        title: "GeeksforGeeks"
    });
});
app.listen(PORT, () => {
    console.log(`Server listening on PORT ${PORT}`);
});

Steps to run the program: 

Run the index.js file using the below command: 

node index.js

Console Output:

Browser Output: Now open a browser or send a GET request using Postman http://localhost:3000/, now on your screen you will see the following output: