In our earlier example of getting user input and storing it a file has only one file. But in real life scenarios, we will have to create multiple file to keep code simple and easy to read.Let’s see how to use module system in node.jsWe have App.js −const http = require('http'); const fs = require('fs'); const server = http.createServer((req, res)=>{    const url = req.url;    if(url === '/'){       res.write('');       res.write(' Hello TutorialsPoint ');       res.write('       Submit ');       res.write('');     ... Read More

Node.js uses only one JavaScript execution thread.Question is − how Node.js process multiple http or any other requests and there can be question on performance, security as well?Node.js starts event loop on application start and handles callback functions using it.Node.js maintains a worker pool. Long running operations are transferred to this worker pool and event pool only handles responses from this worker pool on completion of tasks.Worker pool works with operating system to do the heavy lifting of work and managing scheduling of tasks.Worker pool once finished task responds to event loop using callback functions.Event loop maintains the order of ... Read More

Now, we have a file writing function writeFileSync in fs module as shown below −const requestBody = []; req.on('data', (chunks)=>{    requestBody.push(chunks); }); return req.on('end', ()=>{    const parsedData = Buffer.concat(requestBody).toString();    const username = parsedData.split('=')[1];    fs.writeFileSync('username.txt', username);    //redirect res.statusCode=302;    res.setHeader('Location', '/');    return res.end(); });Sync means synchronized. It’s a blocking code example. Once file write is completed then only code execution for rest of the file starts. Above code is simpler but if we have a large file handling operation it will result into slow performance of app.This way of code execution will slow down the ... Read More

In earlier example in App.js , we saw how to parse data from request using data and end event.Code snippet below shows the if block for that −if(url === '/username' && req.method === 'POST'){    const requestBody = [];    req.on('data', (chunks)=>{       requestBody.push(chunks);    });    req.on('end', ()=>{       const parsedData = Buffer.concat(requestBody).toString();       const username = parsedData.split('=')[1];       fs.writeFileSync('username.txt', username);    });    //redirect    res.statusCode=302;    res.setHeader('Location', '/');    return res.end(); }In above code block, we have two events (data and end) registered if path matches to ‘/username’ and ... Read More

Earlier in simple code example, we saw how to route a request and creating a file to input the test data.Now, we want to save the user entered input data into text file.How Node.js handles incoming request dataNode.js reads data in chunks means it uses streams to read data . Once node completes reading request data, we can proceed to use it for our purpose.First read data in chunks const requestBody = []; req.on(‘data’, (chunks)=>{    requestBody.push(chunks); });We have registred an event called ‘data’ on incoming http request. This event will keep on streaming data and pushes to requestBody const ... Read More

Now we have an App.js file shown below, we want to redirect the user back to ‘/’ once user name is received by node server. We will store user name in a file named username.txtInitial App.js file −const http = require('http'); const server = http.createServer((req, res)=>{    const url = req.url;    if(url === '/'){       res.write('');       res.write(' Hello TutorialsPoint ');       res.write('       Submit ');       res.write('');       return res.end();    }    res.write('');    res.write(' Hello TutorialsPoint '); ... Read More

Routing http requests is important because we want to execute different business rules based on request url and the responses will be different for each routes.Earlier we saw, we can get the url by request.url in node. Simple example of user name input with routes is shown below −const http = require('http'); const server = http.createServer((req, res)=>{    const url = req.url;    if(url === '/'){       res.write('');       res.write(' Hello TutorialsPoint ');       res.write('             Submit ');       res.write('');     ... Read More

App.js −const http = require('http'); const server = http.createServer((req, res)=>{    console.log(req.url, req.method, req. headers); }); server.listen(3000);As shown in above example code, we have request and response parameter object as an argument in createServer method.Response (res) object will be used to send back data to client. It has many properties, some are explained below −res.setHeader(‘Content-Type’, ‘text/html’); this line will set the format of response content o text/html.How to send html content from node.jswrite() function method on response object can be used to send multiple lines of html code like below.res.write(‘’); res.write(‘ Hello TutorialsPoint ’); res.write(‘ Hello Tutorials ... Read More

App.jsconst http = require('http'); const server = http.createServer((req, res)=>{    console.log(req); }); server.listen(3000);Run it with command: node App.jsWe can see what is inside a request object by opening a browser and navigating to localhost:3000There is lots of information which will get printed on console window. We will see some important properties.Identifying the url from where request came, request method type and headers in request is important.Headers will give us information on host and browser type , accepted response by host etc. Request method can be of any http method type like GET, POST, PUT, DELETE etc.const http = require('http'); const ... Read More

Simple http server in node.js will register an event loop which will keep on listening for http requests.Execution of file containing code for creation of server will work as shown below −node App.js => Start executing script => Code parsing, Register events and functions => event loop=> keeps on running as long as event are registered.This is the single threaded event driven approach of the node.js. For accessing and updating of values in database also works using the event driven approach. Even though it’s a single threaded, it can handle multiple requests at a time due to its speed of ... Read More