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When using clusters in Node.js, it's important to understand how clustering works and whether or not a load balancer is necessary. Clustering allows you to create multiple server instances that share the same port, which can be beneficial for utilizing multi-core systems. However, this does not inherently provide any load balancing capabilities on its own.

How Clustering Works in Node.js

When you use cluster module in Node.js, it forks several child processes to handle incoming connections. Each fork listens on the same port and can receive requests for different parts of your application. Here's a basic example:

const cluster = require('cluster');
const http = require('http');
const numCPUs = require('os').cpus().length;

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How to restrict API access to our backend

Here are several approaches to restrict API access to our frontend:

CORS Policy Configuration:

import cors from '@fastify/cors';

fastify.register(cors, {

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How to structure NodeJS project

Possible structures:

File structure

1. Domain-Driven Structure:

src/
├── domains/

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Binary Search Task

Task: We have an array sorted in ascending order:

a = [ 3, 4, 6, 9, 10, 12, 14, 15, 17, 19, 21 ]; Define a function f(a, x) that would return x, the nearest smallest number, or -1 on error.

Example:

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Task

console.log '1' after 1 second,
'2' after 2 seconds and
'3' after 3 seconds after start of the program.

setTimeout

The delay parameter only guarantees that your callback will not execute before that time has elapsed. Other queued tasks or operations could delay it further than the specified time.

const startTime = process.hrtime();

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How to start MongoDB and Mongo Express with docker compose

We use mongo:4.4.6 because of Error: MongoDB 5.0+ requires a CPU with AVX support. Container failed to start Solution from here: https://stackoverflow.com/questions/70818543/mongo-db-deployment-not-working-in-kubernetes-because-processor-doesnt-have-avx You may be can use mongo:latest

docker-compose.yml

version: "3.8"

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Generate a UUID in the browser

const url = URL.createObjectURL(new Blob());
const UUID = url.substring(url.lastIndexOf('/') + 1);

https://medium.com/teads-engineering/generating-uuids-at-scale-on-the-web-2877f529d2a2

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Delete last commit from git

First way

git reset --hard HEAD~1
git push --force

Another way