Дмитрий Беляев

const {promisify} = require('util');
const query = promisify(connection.query.bind(connection));

async function getSomethingFromDB() { // не знаю какое имя у Вас в оригинале
  const result = await query(" SELECT * FROM `tb_1` WHERE `id`=? ", [id]);
  const array = [];
  for (var i in result) {
    // ...
   const result_2 = await query(" SELECT * FROM `tb_2` WHERE `id`=? ", [id]);
    // ...
  }
}

const mysql = require('some-mysql-library');
const app = express();
// ...
function getUserFromMysqlMiddleware(req, res, next) {
  mysql.query('SELECT * FROM `users` WHERE `id`=? LIMIT 1', [req.query.userid]).then(([user]) => {
    if(!user) {
      const err = new Error('Access denied');
      err.status = 403;
      return next(err);
    }
    req.user = user;
    next();
  }).catch(next);
}
app.post('/some/route', getUserFromMysqlMiddleware, (req, res) => {
  // Ваш код с гарантированным наличием req.user
});
app.put('/some/route', getUserFromMysqlMiddleware, (req, res) => {
  // Ваш код с гарантированным наличием req.user
});

я не до конца понимаю, для чего он нужен в принципе

connection.query('SELECT * FROM menu', (err, result) => {
  if(err) {
    console.error(err);
    return;
  }
  const index = result.reduce((acc, row) => ({...acc, [row.id]: row}), {});
  const menu = [];
  for(const row of result) {
    if(row.parent_id === 0) {
      menu.push(row);
      continue;
    }
    const parent = index[row.parent_id];
    if(!parent) {
      console.warn(`Undefined parent with id ${row.parent_id}`);
      continue;
    }
    if(!parent.children) {
      parent.children = [];
    }
    parent.children.push(row);
  }
  console.log(menu);
});

file_load.onsubmit = function(){
  var file = this.elements.myfile.files[0];
  var xhr = new XMLHttpRequest();
  xhr.open("POST", "upload", true);
  xhr.send(file);
  return false;
}

const server = require('http').createServer();
const fs = require('fs');
const nodeStatic = require('node-static');
const file = new nodeStatic.Server('.', {
  cache: 0
});

server.listen(3000, () => console.log("сервер запущен"));
server.on('request', (req, res) => {
  if (req.url == '/upload') {
    req.pipe(
      fs.createWriteStream('file2.jpg')
    ).on('finish', () => res.end('ok'));
    return;
  }
  file.serve(req, res);
});

'ascii' - For 7-bit ASCII data only. This encoding is fast and will strip the high bit if set.

PATH="$PWD/node_modules/.bin:$PATH" postcss --params

{
  "scripts": {
    "postcss": "postcss --params"
  }
}