ExpressJS Form Data Handling

• application/x-www-form-urlencoded Regular HTML forms (key=value pairs)
• multipart/form-data Forms that include file uploads

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

// Parse URL-encoded form data
app.use(express.urlencoded({ extended: true }));

app.post('/submit-form', (req, res) => {
  // Access form data from req.body
  const name = req.body.name;
  const email = req.body.email;
  const message = req.body.message;

  console.log('Form submitted:', { name, email, message });

  res.send(`Thank you ${name}! We received your message.`);
});

  
  
  
  Submit

• { extended: true } Uses the qs library to parse nested objects (like user[name]=John becomes { user: { name: 'John' } })
• { extended: false } Uses the querystring library, which doesn't support nested objects

// Install: npm install multer

const multer = require('multer');
const upload = multer({ dest: 'uploads/' });

// Handle single file upload
app.post('/upload', upload.single('profilePic'), (req, res) => {
  // req.file contains the uploaded file
  console.log(req.file);
  // req.body contains text fields
  console.log(req.body);
  res.send('File uploaded successfully');
});

// Handle multiple files
app.post('/upload-multiple', upload.array('photos', 5), (req, res) => {
  // req.files is an array of uploaded files
  console.log(req.files);
  res.send('Files uploaded');
});

  
  
  Upload

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

// Parse URL-encoded form data
app.use(express.urlencoded({ extended: true }));

// Serve HTML form
app.get('/register', (req, res) => {
  res.send(`
    

      
      
      
              India        USA      
      Register
    

  `);
});

// Handle form submission
app.post('/register', (req, res) => {
  const { username, password, email, country } = req.body;

  // In a real app, you'd validate and save to database
  console.log('New registration:', { username, email, country });

  res.send(`Registration successful! Welcome ${username}`);
});

• Use express.urlencoded({ extended: true }) for regular HTML form data.
• Form data becomes available in req.body.
• For file uploads, use multer middleware.
• The enctype="multipart/form-data" attribute is required in HTML for file uploads.
• Always validate form data on the server never trust client input!