Kannndev

const express = require('express');
const app = express();

function getPi() {
  let sum = 0;
  for (let n = 0; n < 10000000000; n++) {
    let mult = n % 2 === 0 ? 1 : -1;
    sum += mult * (1 / (2 * n + 1));
  }
  return sum * 4;

Kannndev

const express = require('express');
const { Worker } = require('worker_threads');

const app = express();

app.get('/', function (req, res) {
  const worker = new Worker(__dirname + '/worker.js', {
    workerData: { ping: 'pong' },
  });
  worker.on('message', (pi) => {

Kannndev

const Button = styled.button`
  color: blue;
`;

const userQuery = gql`
  {
    users {
      firstName
    }
  }

Kannndev

const generateIntro = (strings, ...values) => {
  console.log(strings); // [ 'My name is ', ' and I am a ', '' ]
  console.log(values); // [ 'Kannan', 'Javascript developer' ]
  let str = '';
   strings.forEach((string, i) => {
       str += string + (values[i] || '');
   });
   return str;
}

Kannndev

const makeBold = (strings, ...values) => {
   let str = '';
   strings.forEach((string, i) => {
       str += `${string} ${values[i] ? `<strong>${values[i]}<strong>` : ''}`;
   });
   return str;
}

const name = 'Kannan';
const role = 'Javascript developer';

Kannndev

import { Test, TestingModule } from '@nestjs/testing'
import { INestApplication, LoggerService } from '@nestjs/common'
import * as request from 'supertest'
import { AppModule } from './../src/app.module'

class TestLogger implements LoggerService {
  log(message: string) {}
  error(message: string, trace: string) {}
  warn(message: string) {}
  debug(message: string) {}

Kannndev

Regular Event Loop

This shows the execution order given JavaScript's Call Stack, Event Loop, and any asynchronous APIs provided in the JS execution environment (in this example; Web APIs in a Browser environment)

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Given the code

Kannndev

System Design Cheatsheet

Picking the right architecture = Picking the right battles + Managing trade-offs

Basic Steps

1. Clarify and agree on the scope of the system

• User cases (description of sequences of events that, taken together, lead to a system doing something useful)
  • Who is going to use it?
  • How are they going to use it?

Kannndev

var udp = require('dgram');

// --------------------creating a udp server --------------------

// creating a udp server
var server = udp.createSocket('udp4');

// emits when any error occurs
server.on('error',function(error){
  console.log('Error: ' + error);

Kannndev

The introduction to Reactive Programming you've been missing

(by @andrestaltz)

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This tutorial as a series of videos

If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.

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