Node.js

// NODE.JS - JavaScript runtime environment - by Beumsk



// ------------------------ NODE ------------------------ //

// node . // run index.js
// node // run node in terminal
// node -v // get node version

// in terminal
process.platform; // returns OS -> darwin(mac), win32(windows), linux...
process.version; // node version
process.env.NAME_OF_VARIABLE; // get .env variable value

// via .js file

// GLOBALS
console.log(__dirname); // /full/path/to/file
console.log(__filename); // /full/path/to/file/index.js


// FROM PACKAGE.JSON
// Extract the arguments from process.argv ("node screenshot.js --url=https://www.example.com --output=example.png")
const args = process.argv.slice(2);
const urlArg = args.find((arg) => arg.startsWith('--url='));
const outputArg = args.find((arg) => arg.startsWith('--output='));
// Extract the values from the argument strings
const url = urlArg ? urlArg.split('=')[1] : '';
const outputPath = outputArg ? outputArg.split('=')[1] : '';


// OS
const os = require('os');
const currentOS = {
  name: os.type(), // name: 'Darwin',
  release: os.release(), // release: '21.6.0',
  totalMem: os.totalmem(), // totalMem: 17179869184,
  freeMem: os.freemem() // freeMem: 2077073408
}
console.log(currentOS);


// PATH
const path = require('path');
console.log(path.sep); // /
const filePath = path.join('create', '//any', 'path.txt');
console.log(filePath); // create/any/path.txt
console.log(path.basename(filePath)); // path.txt
console.log(path.resolve(__dirname, filePath)); // /full/path/to/create/any/path.txt


// ENV VAR
// in .env file: NAME_OF_VARIABLE=thevalue
require('dotenv').config();
const secret = process.env['NAME_OF_VARIABLE'];


// FILE SYSTEM
const {readFile, readFileSync} require('fs');
const txt = readFileSync('./text.txt', 'utf8'); // default way
readFile('./text.txt', 'uft8', (err, txt) => {console.log(txt)}; // non-blocking way
// OR
const { readFile } require('fs').promises;
async function hello() {const file = await readFile('./text.txt', 'utf8')};


// BODY PARSER
// handle data from a form (<form action="/name" method="post")
let bodyParser = require('body-parser');
app.use('/name', bodyParser.urlencoder({extended: false}));
app.post('/name', function(req, res) {
  const name = req.body;
  res.json({'name': name.first + ' ' + name.last});
})




// ------------------------ EXPRESS ------------------------ //

let express = require('express');
// import express from 'express';
let app = express();

const PORT = 8000;
app.listen(PORT, () => console.log('Server is running on port ' + PORT));

// METHODS
app.get('/route', function() {});
app.post('/route', function() {});
app.delete('/route', function() {});
app.put('/route', function() {});

// chain methods with this syntax
app.route('/route').get(function() {}).post(function() {});


// ??ACTIONS??
app.get('/', function(req, res) {
  res.send('Hello World');
  res.sendFile(__dirname + '/index.html'); // needs absolute path
});

app.use('/public', express.static(__dirname + '/public'));

app.get('/json', function(req, res) {
  res.json({"message": "Hello json"});
  const method = req.method; // GET, POST, DELETE, PUT
  const path = req.path; // for example /json
  const ip = req.ip; // ip address
});

app.get('/user/:userId', function(req, res) { // /user/543
  const params = req.params; // route parameters {userId: '543'}
  res.json({'userId': params.userId});
});

app.get('/user', function(req, res) { // /user?userId=543
  const query = req.query; // route query {userId: '543'}
  res.json({'userId': query.userId});
});








// ------------------------ MONGODB ------------------------ //

// https://www.freecodecamp.org/news/get-started-with-mongodb-atlas/
// https://www.freecodecamp.org/news/introduction-to-mongoose-for-mongodb-d2a7aa593c57/
// New project 
// new DB (or cluster) 
// new user with 'read and write to any database' (security > database access)
// access all API (security > network access)
// connect (deployment > database) => mongodb+srv://<username>:<password>@<cluster-name>.prx1c.mongodb.net/<db-name>?retryWrites=true&w=majority
const mongoose = require('mongoose');
mongoose.connect('mongodb+srv://<username>:<password>@<cluster-name>.fnwaqdz.mongodb.net/?retryWrites=true&w=majority', { useNewUrlParser: true, useUnifiedTopology: true })

// create schema
const personSchema = new mongoose.Schema({
  name: { type: String, required: true },
  age: Number,
  favoriteFoods: [String]
});
const Person = mongoose.model('Person', personSchema);

// create record and save
const createAndSavePerson = (done) => {
  var johnDoe = new Person({name: "John Doe", age: 34, favoriteFoods: ['egg', 'meat']});
  johnDoe.save((err, data) => {
    if (err) return console.error(err);
    done(null , data);
  })
};

// create many records
const arrayOfPeople = [
  {name: "Jane", age: 38, favoriteFoods: ['salad']},
  {name: "Jude", age: 31, favoriteFoods: ['fruits']}
];
const createManyPeople = (arrayOfPeople, done) => {  
  Person.create(arrayOfPeople, (err, data) => {
    if (err) return console.error(err);
    done(null , data);
  })
};

// find records
const personName = "Jane";
const findPeopleByName = (personName, done) => {
  Person.find({name: personName}, (err, data) => {
    if (err) return console.error(err);    
    done(null , data);
  });
};

// find one record
const food = ['salad'];
const findOneByFood = (food, done) => {
  Person.findOne({favoriteFoods: food}, (err, data) => {
    if (err) return console.error(err);    
    done(null , data);
  });
};

// find by _id
const personId = 1;
const findPersonById = (personId, done) => {
  Person.findById(personId, (err, data) => {
    if (err) return console.error(err);    
    done(null , data);
  });
};

// classic way of updating
const foodToAdd = "hamburger";
const findEditThenSave = (personId, done) => {
  Person.findById(personId, (err, data) => {
    if(err) return console.log(err); 
    data.favoriteFoods.push(foodToAdd);
    data.save((err, updatedPerson) => {
      if(err) return console.log(err);
      done(null, updatedPerson)
    });
  });
};

// new way of updating (similar: findByIdAndUpdate)
const ageToSet = 20;
const findAndUpdate = (personName, done) => {
  Person.findOneAndUpdate({name: personName}, {age: ageToSet}, { new: true }, (err, data) => {
    if(err) return console.log(err);
    done(null , data);
  });
};

// rmove by _id (similar: findOneAndRemove)
const removeById = (personId, done) => {
  Person.findByIdAndRemove(personId, (err, data) => {
    if(err) return console.log(err);
    done(null , data);
  });
};

// remove
const removeManyPeople = (done) => {
  const nameToRemove = "Mary";
  Person.remove({name: nameToRemove}, (err, data) => {
    if(err) return console.log(err);
    done(null , data);
  });
};

// chain search query helpers
const queryChain = (done) => {
  const foodToSearch = "burrito";
  Person.find({favoriteFoods: foodToSearch})
    .sort({name: 1})
    .limit(2)
    .select({age: 0})
    .exec((err, data) => {
      if(err) return console.log(err);
      done(null , data);
    })
};