Lihour lihourchhin

Node.js Deployment

Steps to deploy a Node.js app to DigitalOcean using PM2, NGINX as a reverse proxy and an SSL from LetsEncrypt

1. Sign up for Digital Ocean

If you use the referal link below, you get $10 free (1 or 2 months) https://m.do.co/c/5424d440c63a

2. Create a droplet and log in via ssh

I will be using the root user, but would suggest creating a new user

Advanced memoization and effects in React

Memoization is a somewhat fraught topic in the React world, meaning that it's easy to go wrong with it, for example, by [making memo() do nothing][memo-pitfall] by passing in children to a component. The general advice is to avoid memoization until the profiler tells you to optimize, but not all use cases are general, and even in the general use case you can find tricky nuances.

Discussing this topic requires some groundwork about the technical terms, and I'm placing these in once place so that it's easy to skim and skip over:

Memoization means caching the output based on the input; in the case of functions, it means caching the return value based on the arguments.
Values and references are unfortunately overloaded terms that can refer to the low-level implementation details of assignments in a language like C++, for example, or to memory allocation (i.e., value and reference types in C#), but that should just be ignored in JavaScript, because "pass b

Git Cheat Sheet

Initial Setup

Initialize a repo

Create an empty git repo or reinitialize an existing one

$ git init

	if [ ! -f .env ]
	then
	export $(cat .env \| xargs)
	fi

	import React, { Component } from 'react'
	import PropTypes from 'prop-types'

	/**
	* Utils
	*/
	const removeElementByIds = ids => {
	ids.forEach(id => {
	const element = document.getElementById(id)
	if (element && element.parentNode) {

	#!/bin/sh
	#
	# chmodr.sh
	#
	# author: Francis Byrne
	# date: 2011/02/12
	#
	# Generic Script for recursively setting permissions for directories and files
	# to defined or default permissions using chmod.
	#

	class FetchDataFromRSSFeed extends Component {
	constructor() {
	super();
	this.state = {
	recentBlogPost: {
	name: '',
	url: ''
	}
	}
	}

	package com.cubetiqs.factory

	import org.junit.jupiter.api.Assertions
	import org.junit.jupiter.api.Test

	class FactoryTests {

	@Test
	fun factoryTest() {
	val carA = CarFactory(CarType.CAR_A).getCar()

	const arr1 = [1,2,3]
	const arr2 = [4,5,6]
	const arr3 = [...arr1, ...arr2] //arr3 ==> [1,2,3,4,5,6]