Mohan Kumar mohankumar-i2i

Better local require() paths for Node.js

Problem

When the directory structure of your Node.js application (not library!) has some depth, you end up with a lot of annoying relative paths in your require calls like:

const Article = require('../../../../app/models/article');

Those suck for maintenance and they're ugly.

Possible solutions

Data Modeling with MongoDB

Objectives

Understand model relationships in MongoDB
Understand One-to-Many relationships

And my article is deprecated!

As of just writing this, Express 4.0 was released and there are points in there that no longer matter. So, this remains as a great >4.0 article.

Node.js is the red-hot new hotness! You can't throw a stick on the internet without hitting someone talking about Node. But why? For one, it's built on JavaScript which is completely ubiquitous. So, why not build a development stack and server on JavaScript? I would argue that the installation is almost painless while the terseness of the language is not.

While you can create apps 100% from Node.js, the Express framework is a great tool that helps you solve many standard problems without having to write boilerplate code.

Node.js is here and it's not going anywhere anytime soon. So if you are new to Node.js, Express, and even JavaScript in general, this is a great newb's step-by-step guide to get started.

	#!/bin/bash
	# install httpd (Linux 2 version)
	# create role with s3 write access privilege and set to ec2 instance
	yum update -y
	yum install -y httpd
	systemctl start httpd
	systemctl enable httpd
	usermod -a -G apache ec2-user
	chown -R ec2-user:apache /var/www/html
	chmod 2775 /var/www/html

	const cluster = require("cluster");
	const express = require("express");
	const numCPUs = require("os").cpus().length;
	const app = require
	if (cluster.isMaster) {
	console.log(`Master ${process.pid} is running`);

	// Fork workers.
	for (let i = 0; i < numCPUs; i++) {
	cluster.fork();

	var fs = require('fs');
	const cache = {};

	function readFile(fileName, callback) {
	if (cache[fileName]) {
	return callback(null, cache[fileName])
	}
	fs.readFile(fileName, (err, fileContent) => {
	if (err) {
	console.log(err);

	const https = require('https');
	const crypto = require('crypto');
	const fs = require('fs');

	const start = Date.now();

	setImmediate(() => console.log('this is set immediate 1'));
	setImmediate(() => console.log('this is set immediate 2'));
	setImmediate(() => console.log('this is set immediate 3'));

	const crypto = require("crypto");
	const start = Date.now();

	function logHashTime(label) {
	crypto.pbkdf2("a", "b", 100000, 512, "sha512", () => {
	console.log("Hash-"+label+": ", Date.now() - start);
	});
	}
	logHashTime(1);
	logHashTime(2);

	# Install Pre-requisites
	apt update
	apt install apt-transport-https ca-certificates curl software-properties-common -y
	curl -fsSL https://download.docker.com/linux/ubuntu/gpg \| apt-key add -
	add-apt-repository "deb [arch=amd64] https://download.docker.com/linux/ubuntu $(lsb_release -cs) stable"
	apt update

	# Install Docker CE
	apt install docker-ce -y

	const waitFor = (ms) => new Promise(r => setTimeout(r, ms))
	const asyncForEach = (array, callback) => {
	for (let index = 0; index < array.length; index++) {
	await callback(array[index], index, array)
	}
	}

	const start = async () => {
	await asyncForEach([1, 2, 3], async (num) => {
	await waitFor(50)