alex-alekseichuk

<select id="selectOptgroup" defaultValue="">
  <option disabled="disabled" value="">Select option...</option>
  <optgroup label="First section">
    <option value="1.1">1.1</option>
    <option value="1.2">1.2</option>
  </optgroup>
  <optgroup label="Second section">
    <option value="2.1">2.1</option>
    <option value="2.2">2.2</option>
  </optgroup>

alex-alekseichuk

#!/usr/bin/bash
echo -n 'Password: '
read -s password
plain=$(mktemp)
openssl enc -aes-256-cbc -pbkdf2 -iter 100000 -pass pass:$password -d <$1 >$plain 2>/dev/null
prev=$(mktemp)
cp $plain $prev
vi $plain
if ! (cmp -s $prev $plain); then
  openssl enc -aes-256-cbc -pbkdf2 -iter 100000 -pass pass:$password <$plain >$1 2>/dev/null

alex-alekseichuk

/**
  npm i --save mysql
  
  
  const conn = await pool.getAsyncConnection();
  await conn.beginTransaction();
  try {
    await conn.query(sql1);
    await conn.query(sql2);
    await conn.commit();

alex-alekseichuk

/*
    SHA256 pure JavaScript implementation.

    const hexContent = '278f0c9f473ddca628240ac41bfab9fec90612a929ad2d7b';
    const aContent = hexToBytes(hexContent);

    const hash = createHash('sha256');
    hash.update(aContent);

    const aHash = hash.digest();

alex-alekseichuk

const isTokenExpired = token => Date.now() >= (JSON.parse(atob(token.split('.')[1]))).exp * 1000;

alex-alekseichuk

// node ./mem-limit-test.js
// node --max-old-space-size=4096 ./mem-limit-test.js
// NODE_OPTIONS=--max-old-space-size=4096 node ./mem-limit-test.js
const array = [];
while (true) {
  // increase array
  array.push(new Array(10000000));

  const memory = process.memoryUsage();
  console.log((memory.heapUsed / 1024 / 1024 / 1024).toFixed(4), 'GB');

alex-alekseichuk

// Nullish coalescing
// Нулевое слияние
// if data is undefined
const getUserName = (user) => {
  return user?.name ?? "Anonymous";
};

// will display `fallbackData`
// if data is false-ish (e.g., null, undefined, '', 0, etc.)
console.log(data || fallbackData);

alex-alekseichuk

#!/usr/bin/env node

function createFizzBuzzGenerator() {
  const values = Array(16).fill(null).map((_, i) => {
    const x = i + 1
    if (x % 3 !== 0 && x % 5 !== 0)
      return x
    let result = ''
    if (x % 3 === 0)
      result += 'Fizz'

alex-alekseichuk

// Test task: check if brackets string balanced

const bracketsMatch = {
  '{': '}',
  '[': ']',
  '(': ')',
}

function isBalanced(brackets) {
  const stack = []

alex-alekseichuk

// Brute-force solution of the Zebra Puzzle
// https://code.energy/solving-zebra-puzzle/
//
// Result:
// Norwegian from 1 house drinks water.
// Japanese from 5 house owns zebra.

package main

import (