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What is chunk in Node.js ?

  • Difficulty Level : Basic
  • Last Updated : 26 May, 2021
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The data is a transfer from server to client for a particular request in the form of a stream. The stream contains chunks. A chunk is a fragment of the data that is sent by the client to server all chunks concepts to each other to make a buffer of the stream then the buffer is converted into meaning full data. In this article, we will discuss how to send chunks from the request body to the server. The request object is used for handling the chunks of data.

Syntax:

request.on('eventName',callback)

Parameters: This function accepts the following two parameters:

  • eventName: It is the name of the event that fired
  • callback: It is the Callback function i.e Event handler of the particular event.

Return type: The return type of this method is void.

Example: Create an index.js file with the following code.



index.js




// Importing http libraries
const http = require('http');
  
// Creating a server
const server = http.createServer((req, res) => {
    const url = req.url;
    const method = req.method;
  
    if (url === '/') {
        // Sending the response
        res.write('<html>');
        res.write('<head><title>Enter Message</title><head>');
        res.write(`<body><form action="/message" method="POST">
    <input type="text" name="message"></input>
    <button type="submit">Send</button></form></body></html>`);
        res.write('</html>');
        return res.end();
    }
  
    // Handling different routes for different type request
    if (url === '/message' && method === 'POST') {
        const body = [];
  
        req.on('data', (chunk) => {
  
            // Storing the chunk data
            body.push(chunk);
            console.log(body)
        });
  
        req.on('end', () => {
  
            // Parsing the chunk data
            const parsedBody = Buffer.concat(body).toString();
            const message = parsedBody.split('=')[1];
              
            // Printing the data
            console.log(message);
        });
  
        res.statusCode = 302;
        res.setHeader('Location', '/');
        return res.end();
    }
});
  
// Starting the server
server.listen(3000);

Run index.js file using below command:

node index.js

Now open a browser and go to http://localhost:3000, you will see the following output.

Console Output:




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