What is Node.js?
Node.js® is a JavaScript runtime built on Chrome's V8 JavaScript engine. Node.js uses an event-driven, non-blocking I/O model that makes it lightweight and efficient.
What is it used for?
- web servers, so creating dynamic websites
- set up a local web development environment
- easier to build desktop applications with Electron: Slack, Visual Code, Atom
- some of the biggest companies use Node.js in production: Netflix, Walmart, IBM, etc.
- JavaScript everywhere (used to be PHP, Python, JavaScript, MySQL, Apache, now JavaScript full stack)
A simple Node.js server
Simple server ``js const http = require('http');
const server = http.createServer(function (req, res) { res.end("Hello World!") });
server.listen(5000);
console.log('Node.js web server at port 5000 is running..')
**Server with two routes**
``js
const http = require('http');
const server = http.createServer(function (req, res) {
if (req.url === '/') { //check the URL of the current request
console.log("New request to main page at " + Date())
// set response header
res.writeHead(200, { 'Content-Type': 'text/html' });
// set response content
res.write('<html><body><h1>This is home Page.</h1></body></html>');
res.write('<h2>The time is: ' + Date() + '</h2>');
res.end();
} else if (req.url === "/student") {
console.log("New request to Student page at " + Date())
res.writeHead(200, { 'Content-Type': 'text/html' });
res.write('<html><body><h1>This is student Page.</h1></body></html>');
res.end();
} else {
res.end('<html><body><h2>Invalid Request at ' + Date() + '</h2></body></html>');
}
});
server.listen(5000);
console.log('Node.js web server at port 5000 is running..')
Exercise
Can you add another route /mentor?