Understanding express.json() in Express.js

• When building a backend application with express, handling a incoming request data is common.
• One of the most frequently used type of data is JSON.
• This is where express comes to play.

express.json() reads JSON data in the incoming request body and converts into Javascript Object that can easily access in route handlers.

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Why Do We Need express.json()?

HTTP requests often send data in the body, especially in POST requests. Without parsing, Express doesn’t automatically understand JSON format.

For example:

{
  "name": "Vasanth",
  "email": "[e-mail]"
}

If try to access req.body without using express.json(), it will be undefined.

app.post('/users', (req, res) => {
    console.log(req.body.name); // Works only if express.json() is used
    res.send('User received');
});

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How to Use express.json()

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

// Middleware to parse JSON data
app.use(express.json());

app.post('/users', (req, res) => {
    const user = req.body;
    res.send(`User ${user.name} with email ${user.email} added successfully!`);
});

app.listen(8000, () => {
    console.log('Server running on port 8000');
});