How to access the request body when POSTing using Node.js and Express?

Starting from express v4.16 there is no need to require any additional modules, just use the built-in JSON middleware:

app.use(express.json())

Like this:

const express = require('express')

app.use(express.json())    // <==== parse request body as JSON

app.listen(8080)

app.post('/test', (req, res) => {
  res.json({requestBody: req.body})  // <==== req.body will be a parsed JSON object
})

Note - body-parser, on which this depends, is already included with express.

Also don't forget to send the header Content-Type: application/json

For 2019, you don't need to install body-parser.

You can use:

var express = require('express');
var app = express();
app.use(express.json())
app.use(express.urlencoded({extended: true}))
app.listen(8888);
app.post('/update', function(req, res) {
    console.log(req.body); // the posted data
});

You should not use body-parser it is deprecated. Try this instead

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

app.use(express.json()) //Notice express.json middleware

The app.use() function is used to mount the specified middleware function(s) at the path which is being specified. It is mostly used to set up middleware for your application.

Now to access the body just do the following

app.post('/', (req, res) => {
  console.log(req.body)
})

This can be achieved without body-parser dependency as well, listen to request:data and request:end and return the response on end of request, refer below code sample. ref:https://nodejs.org/en/docs/guides/anatomy-of-an-http-transaction/#request-body

var express = require('express');
var app = express.createServer(express.logger());

app.post('/', function(request, response) {

    // push the data to body
    var body = [];
    request.on('data', (chunk) => {
      body.push(chunk);
    }).on('end', () => {
      // on end of data, perform necessary action
      body = Buffer.concat(body).toString();
      response.write(request.body.user);
      response.end();
    });
});

In my case, I was missing to set the header:

"Content-Type: application/json"

The accepted answer only works for a body that is compatible with the JSON format. In general, the body can be accessed using

app.use(
  Express.raw({
    inflate: true,
    limit: '50mb',
    type: () => true, // this matches all content types
  })
);

like posted here. The req.body has a Buffer type and can be converted into the desired format.

For example into a string via:

let body = req.body.toString()

Or into JSON via:

let body = req.body.toJSON();

If you're lazy enough to read chunks of post data. you could simply paste below lines to read json.

Below is for TypeScript similar can be done for JS as well.

app.ts

 import bodyParser from "body-parser";
 // support application/json type post data
 this.app.use(bodyParser.json());
 // support application/x-www-form-urlencoded post data
 this.app.use(bodyParser.urlencoded({ extended: false }));

In one of your any controller which receives POST call use as shown below

userController.ts

 public async POSTUser(_req: Request, _res: Response) {
   try {
          const onRecord = <UserModel>_req.body;
           /* Your business logic */
           _res.status(201).send("User Created");
        }
    else{
           _res.status(500).send("Server error");
           }        
   };

_req.body should be parsing you json data into your TS Model.

I'm absolutely new to JS and ES, but what seems to work for me is just this:

JSON.stringify(req.body)

Let me know if there's anything wrong with it!

Install Body Parser by below command

$ npm install --save body-parser

Configure Body Parser

const bodyParser = require('body-parser');
app.use(bodyParser);
app.use(bodyParser.json()); //Make sure u have added this line
app.use(bodyParser.urlencoded({ extended: false }));