Difference between app.use(express.json()) and app.use(bodyParser.json())

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When you working with Express.js you might see Both app.use(express.json()); and app.use(bodyParser.json()); in deferent sources.

app.use(express.json()); and app.use(bodyParser.json()); are used to parse incoming request bodies as JSON in Express.js, but there are a few differences between them.

express.json()

This is a build-in-method in Express.js after 4.16.0 version to parse JSON bodies. Prior to this version, Express used body-parser as a middleware to parse JSON. Since this is a built-in middleware, don’t need to install body-parser separately.

bodyParser.json()

This is a separate package that need to install. It’s a middleware used by older versions of Express before express.json() was added.

Main Differences

Functionality:

• Both express.json() and bodyParser.json() provide the same functionality for parsing JSON bodies.
• express.json() is essentially a wrapper around body-parser’s json() function since Express started using body-parser internally in version 4.16.0.

Built-in vs. External:

• express.json() is built into Express 4.16.0 and later, so you don't need any additional package.
• bodyParser.json() requires you to install the body-parser package separately.

Performance:

• Since express.json() is built into Express, there is no overhead of an external package like body-parser. It can be slightly more efficient if you're only using Express's JSON parsing.

Usage

bodyParser.json()

const bodyParser = require('body-parser');
app.use(bodyParser.json());

express.json()

app.use(express.json());

Conclusion:

• If you’re using Express 4.16.0 or later, it is recommended to use express.json() since it is built-in and eliminates the need for an external dependency.
• If you’re working with an older version of Express or if you’re already using body-parser for other purposes, you can continue using bodyParser.json().