1. Basics
2. Creating a Simple Server
const http = require('http');
const server = http.createServer((req, res) => {
res.statusCode = 200;
res.setHeader('Content-Type', 'text/plain');
res.end('Hello, World!n');
});
server.listen(3000, '127.0.0.1', () => {
console.log('Server running at http://127.0.0.1:3000/');
});
3. File System Operations
- Read File:
const fs = require('fs');
fs.readFile('example.txt', 'utf8', (err, data) => {
if (err) throw err;
console.log(data);
});
- Write File:
fs.writeFile('example.txt', 'Hello, Node!', (err) => {
if (err) throw err;
console.log('File has been saved!');
});
4. Modules
- Create a Module:
// myModule.js
const greeting = (name) => `Hello, ${name}!`;
module.exports = greeting;
- Import a Module:
const greeting = require('./myModule');
console.log(greeting('World'));
5. NPM Commands
- Initialize Project:
- Install Package:
- Uninstall Package:
npm uninstall package-name
- List Installed Packages:
6. Asynchronous Programming
- Callback Example:
function fetchData(callback) {
setTimeout(() => {
callback('Data fetched');
}, 1000);
}
fetchData((data) => {
console.log(data);
});
- Promises:
const fetchData = () => {
return new Promise((resolve, reject) => {
setTimeout(() => {
resolve('Data fetched');
}, 1000);
});
};
fetchData().then(data => console.log(data));
- Async/Await:
const fetchData = async () => {
return 'Data fetched';
};
const getData = async () => {
const data = await fetchData();
console.log(data);
};
getData();
7. Express.js Framework
- Setting Up Express:
- Basic Express Server:
const express = require('express');
const app = express();
app.get('/', (req, res) => {
res.send('Hello, Express!');
});
app.listen(3000, () => {
console.log('Server running on http://localhost:3000');
});
8. Debugging
- Debug with Node:
- Using Chrome DevTools:
node --inspect yourfile.js
9. Commonly Used Modules
- Path:
const path = require('path');
console.log(path.join(__dirname, 'file.txt'));
- OS:
const os = require('os');
console.log(os.platform());
- HTTP:
const http = require('http');
10. Tips
- Use
nodemon for auto-reloading during development:
npm install -g nodemon
nodemon yourfile.js
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