Express.js res.json() Function

Last Updated : 07 Jul, 2020

The res.json() function sends a JSON response. This method sends a response (with the correct content-type) that is the parameter converted to a JSON string using the JSON.stringify() method.

Syntax:

res.json( [body] )

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

Return Value: It retuns an Object.

Installation of express module:

You can visit the link to Install express module. You can install this package by using this command.
```
npm install express
```
After installing the express module, you can check your express version in command prompt using the command.
```
npm version express
```
After that, you can just create a folder and add a file for example, index.js. To run this file you need to run the following command.
```
node index.js
```

Example 1: Filename: index.js

var express = require('express'); 
var app = express(); 
var PORT = 3000; 
  
// Without middleware 
app.get('/', function(req, res){ 
    res.json({ user: 'geek' }); 
}); 
  
app.listen(PORT, function(err){ 
    if (err) console.log(err); 
    console.log("Server listening on PORT", PORT); 
}); 

Steps to run the program:

The project structure will look like this:
Make sure you have installed express module using the following command:
```
npm install express
```
Run index.js file using below command:
```
node index.js
```
Output:
```
Server listening on PORT 3000
```
Now open browser and go to http://localhost:3000/, now on your screen you will see the following output:
```
{"user":"geek"}
```

Example 2: Filename: index.js

var express = require('express'); 
var app = express(); 
var PORT = 3000; 
  
// With middlware 
app.use('/', function(req, res, next){ 
    res.json({title: "GeeksforGeeks"}) 
    next(); 
}) 
  
app.get('/', function(req, res){ 
     console.log("User Page") 
     res.end(); 
}); 
  
app.listen(PORT, function(err){ 
    if (err) console.log(err); 
    console.log("Server listening on PORT", PORT); 
});