Difference between res.send() and res.json() in Express.js?

In this article, we will learn about res.send() & res.json(), along with discussing the significant distinction that differentiates between res.send() & res.json().

Let us first understand what is res.send() and res.json() in Express.js?

res.send() - The res.send() function is used for sending the response for the HTTP request. It takes a parameter body. The parameter can be a String, Buffer object, an object, Boolean, or an Array.

Syntax:

res.send( [body] )

Parameter: The body parameter takes a single argument that describes the body that is to be sent in the response.

Content Type: The Express sets the content type of the parameter according to the type of the body parameter.

• String & HTML - “text/html”
• Buffer - “application/octet-stream”
• Array & object - "application/json"

Return Type: It is used to send a response to the client and then ends the response process. The method itself doesn't return anything.

Example: This example demonstrate the simple res.send().

const express = require('express');
const app = express();
const PORT = 8000;

app.get('/', (req, res)=>{
    res.send('Hello World')
  });
  
app.listen(PORT, ()=>{
    console.log(`Server is listening to port: ${PORT}`)
  });

Output:

• Console output:

Server is listening to port: 8000

• Browser Output:

res.json() - The res.json() function sends the response as JSON format. It automatically converts the JavaScript object into a JSON-formatted string. The parameter body can be of any JSON type, which includes object, array, string, Boolean, number, or null.

res.json() will also convert non-objects, such as null and undefined, which are not valid JSON.

Syntax:

res.json( [body] )

Parameter: The body parameter takes JavaScript Object as its argument.

Content Type: Its content-type is set to - "application/json".

Returns: It is used to send JSON response to the client and then ends the response process.

Example: This example demonstrate the simple res.send().

const express = require('express');
const app = express();
const PORT = 8000;

const data =  [
    {id: 1, name: 'GFG'},
    {id: 2, name: 'Express'}
   ]

app.get('/', (req, res)=>{
    res.json(data)
  });
  
app.listen(PORT, ()=>{
    console.log(`Server is listening to port: ${PORT}`)
  });

Output:

• Console output:

Server is listening to port: 8000

• Browser Output:

Difference between res.send() and res.json():

Through both res.send() and res.json() seems to identical and fulfill similar purposes but still there is significant contrast that differentiates both res.send() and res.json(), which is given below.

Conclusion:

Both res.send() and res.json() serves similar purposes with some difference. So it depends on the data type which we are working with. Choose res.json() when you are specifically working with JSON data. Use res.send() when you need versatility and control over the content type or when dealing with various data types in your responses.