SarasArya

The operating system used here is Ubuntu
Download and install Pycharm-edu
Open it and create a New Project
This will create a project folder and install all necessary base files
now inside that folder and create a virtual environment by typing `virtualenv -p /usr/bin/python3.4 <venv_name>`
Type `source <venv_name>/bin/activate` to activate that virtual environment. Node people consider this as your local node_modules folder. 
Now install Django by typing `pip3 install Django`
This will create the django-admin.py file necessary to start a project.
Create your sub-app by typing `django-admin.py startproject <my_sub_app>`
This will create another folder with the name <sub_app>

SarasArya

MONGO_DATABASE="your_db_name"
APP_NAME="your_app_name" #this is optional.Use this if you have more than 1 scripts for more than 1 app
MONGO_HOST="<db_name>/server0.example.com:27011,server1.example.com:27011,server2.example.com:27011" #for replica set config
#MONGO_HOST="127.0.0.1" in case running a standalone server
#MONGO_PORT=27001 in case running a standalone server on a port other than 27017
TIMESTAMP=`date +"%d-%m-%y"`
MONGODUMP_PATH="/usr/bin/mongodump" #got it from whereis mongodump 
#BACKUP_DIR="/home/oroborus/work/server-logs" #for my local machine to test it out
BACKUP_DIR="/home/ubuntu/server-logs" #ec2 instance where to put it
BACKUP_NAME="$APP_NAME/$TIMESTAMP" #folder structure optional again

SarasArya

// This file provides an example of how you can expose both Promises and callback support to your functions

const fs = require('fs');
//This function can be called via callbacks, as well as Promises
const readFileAsArray = function(file, cb = () => {}) { //callback is made an empty function in case I am using Promises,
    // in which case I wont be passing this argument and it wouldn't throw and undefined variable error.
    return new Promise((resolve, reject) => { //create a new promise
        fs.readFile(file, (err, data) => {
            if (err) {
                reject(err); //To support promises 

SarasArya

const salary = 246250;
const taxExempt = 250000;
const limit1 = 250000;
const taxPercentage1 = 0.1 // This should be changed to 0.05 from 2017-2018 fiscal
const limit2 = 500000;
const taxPercentage2 = 0.2
const limit3 = 1000000;
const taxPercentage3 = 0.3;
let taxBracket = null;
//decide the tax bracket that you lie in

SarasArya

//On instruction of how to debug if sockets are working or not. Please check here https://socket.io/docs/logging-and-debugging/

//NodeJS Side

const server = require('http').Server(app),
    io = require('socket.io')(server);

io.sockets.on('connection', function (socket) {
    socket.on('set', function (status, callback) {
        console.log(status);

SarasArya

//To remove a field from each document. Whenever I introduce a field by mistake 
db.example.update({}, {$unset: {words:1}} , {multi: true});

//To search in array of objects in mongodb
db.collection.find( { field1: { $elemMatch: { one: 1 } } } );

//To update array of objects in mongodb console
db.roles.update({"userId" : ObjectId("58a191b8d02dde3638a5a4ee"), "children.requestStatus" : 'Rejected'},{$set : {"children.$.requestStatus" : "Authorized"}})

SarasArya

process.stdout.write('\u001B[2J\u001B[0;0f'); // Cleans up the console. 

const server = require('net').createServer(); 
let counter = 0;
let sockets = {};
//function to return the current time
let timeStamp = () => {
	let now = new Date();
	return `${now.getHours()}:${now.getMinutes()}`
};

SarasArya

server {
        listen 80;
        server_name www.example.com example.com;
        return 301 https://$host$request_uri;
}
server {
        listen 443 ssl;
        server_name www.example.com;

        ssl_certificate /etc/letsencrypt/live/example.com/fullchain.pem;

SarasArya

const rp = require('request-promise');
const urls = ['https://jsonplaceholder.typicode.com/todos/1', 'https://jsonplaceholder.typicode.com/todos/2'];

const newUrls = urls.map(url => () => rp(url));

Promise.resolve()
    .then(x => newUrls[0]())
    .then(x => newUrls[1]());

console.log(newUrls);

SarasArya

const NEWER = Symbol("newer");
const OLDER = Symbol("older");

class LRU {
  constructor(limit = 10) {
    this.limit;
    this.size;
    this.cache = new Map();
    this.newest = undefined;
    this.oldest = undefined;