bodyParser.json() vs express.json() & express.urlencoded() vs express.json()

Earlier versions of Express used to have a lot of middleware bundled with it. bodyParser was one of the middlewares that came it.

What is Middleware?

It is those methods/functions/operations that are called BETWEEN processing the Request and sending the Response in your application method.

bodyParser.json() vs express.json()

Node/Express Framework has been used to install another piece of middleware in order for us to be able to read the “body” of an incoming JSON object. This piece of middleware was called body-parser and used to not be part of the Express framework.

When Express 4.0 was released they decided to remove the bundled middleware from Express and make them separate packages instead. The syntax then changed from app.use(express.json()) to app.use(bodyParser.json()) after installing the body-parser module.

// calling body-parser to handle the Request Object from POST requests
var bodyParser = require('body-parser');
// parse application/json, basically parse incoming Request Object as a JSON Object 
app.use(bodyParser.json());
// parse application/x-www-form-urlencoded, basically can only parse incoming Request Object if strings or arrays
app.use(bodyParser.urlencoded({ extended: false }));
// combines the 2 above, then you can parse incoming Request Object if object, with nested objects, or generally any type.
app.use(bodyParser.urlencoded({ extended: true }));

body-parser was added back to Express in release 4.16.0. That means you don’t have to use bodyParser.json() anymore if you are on the latest release. You can use express.json() instead. Their own body-parser implementation is now included in the default Express package so there is no need for you to download another dependency.

// parse application/json, basically parse incoming Request Object as a JSON Object 
app.use(express.json());
// parse application/x-www-form-urlencoded, basically can only parse incoming Request Object if strings or arrays
app.use(express.urlencoded({ extended: false }));
// parse incoming Request Object if object, with nested objects, or generally any type.
app.use(express.urlencoded({ extended: true }));

note: There are still some very specific cases where body-parser might still be necessary but for the most part Express’ implementation of body-parser is all you will need for the majority of use cases.

express.json() vs express.urlencoded()

Here is the explanation that should clear doubts on express.json() and express.urlencoded() and the use of body-parser.

When talking about express.json() and express.urlencoded() think specifically about POST requests (i.e. the .post request object) and PUT Requests (i.e. the .put request object).You DO NOT NEED express.json() and express.urlencoded() for GET Requests or DELETE Requests.You NEED express.json() and express.urlencoded() for POST and PUT requests, because in both these requests you are sending data (in the form of some data object) to the server and you are asking the server to accept or store that data (object), which is enclosed in the body (i.e. req.body) of that (POST or PUT) Request.

express.json() is a method inbuilt in express to recognize the incoming Request Object as a JSON Object. This method is called as a middleware in your application using the code: app.use(express.json());

express.urlencoded() is a method inbuilt in express to recognize the incoming Request Object as strings or arrays. This method is called as a middleware in your application using the code: app.use(express.urlencoded());

// parse application/json, basically parse incoming Request Object as a JSON Object 
app.use(express.json());
// parse application/x-www-form-urlencoded, basically can only parse incoming Request Object if strings or arrays
app.use(express.urlencoded({ extended: false }));
// parse incoming Request Object if object, with nested objects, or generally any type.
app.use(express.urlencoded({ extended: true }));

note: extended This option allows choosing between parsing the URL-encoded data with the query string library (when false) or the qs library (when true).