Get HTTP request body data using Node

Find out how to extract the data sent as JSON through an HTTP request body using Node

⭐️ 👀 2023 WEB DEVELOPMENT BOOTCAMP starting in days! Join the waiting list to reserve your spot in my 10-weeks cohort course and learn the fundamentals, HTML, CSS, JS, Tailwind, React, Next.js and much much more! 👀 ⭐️

Here is how you can extract the data that was sent as JSON in the request body.

If you are using Express, that’s quite simple: use the body-parser Node module.

For example, to get the body of this request:

const axios = require('axios')

axios.post('/todos', {
  todo: 'Buy the milk',
})

This is the matching server-side code:

const bodyParser = require('body-parser')

app.use(
  bodyParser.urlencoded({
    extended: true,
  })
)

app.use(bodyParser.json())

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

If you’re not using Express and you want to do this in vanilla Node, you need to do a bit more work, of course, as Express abstracts a lot of this for you.

The key thing to understand is that when you initialize the HTTP server using http.createServer(), the callback is called when the server got all the HTTP headers, but not the request body.

The request object passed in the connection callback is a stream.

So, we must listen for the body content to be processed, and it’s processed in chunks.

We first get the data by listening to the stream data events, and when the data ends, the stream end event is called, once:

const server = http.createServer((req, res) => {
  // we can access HTTP headers
  req.on('data', (chunk) => {
    console.log(`Data chunk available: ${chunk}`)
  })
  req.on('end', () => {
    //end of data
  })
})

So to access the data, assuming we expect to receive a string, we must put it into an array:

const server = http.createServer((req, res) => {
  let data = []
  req.on('data', (chunk) => {
    data.push(chunk)
  })
  req.on('end', () => {
    JSON.parse(data).todo // 'Buy the milk'
  })
})

One more thing! ⚠️ ✋

At the end of January I will organize the Web Development Bootcamp.

It's a 10-weeks long cohort online course where I will guide you to becoming a Web Developer.

It's not "just a course". It's a big event I organize once a year.

We'll start from zero, learn the fundamentals of Web Development, HTML CSS, JavaScript, Tailwind, Git, using the command line, VS Code, GitHub, Node.js, we'll then learn React, JSX, how to use PostgreSQL, Astro, Next.js, Prisma, deploying on Netlify/DigitalOcean/Fly/Vercel and much more! 

At the end of the first 10 weeks you'll know how to create web sites and web applications and I'll unlock you the 2nd phase of the Bootcamp: you will get access to a large number of projects exclusive to the Bootcamp graduates, so you can follow my instructions to build things like private areas with authentication, clones of popular sites like Twitter YouTube Reddit, create e-commerce sites, and much much more.

Because once you got the fundamentals, you only learn by working on real, exciting projects.

To find out more, visit bootcamp.dev