AIでも壊れない堅牢コードへ鍛え直す！
コードレビュー道場 #3：非機能要件

async function transfer(db, fromId, toId, amount) {
  await db.execute(
    'UPDATE accounts SET balance = balance - ? WHERE id = ?',
    [amount, fromId]
  );
  await db.execute(
    'UPDATE accounts SET balance = balance + ? WHERE id = ?',
    [amount, toId]
  );
}

async function fetchProfile(userId) {
  const res = await fetch(`https://api.example.com/users/${userId}`);
  if (!res.ok) {
    throw new Error('failed');
  }
  return res.json();
}

const logs = [];

function logEvent(event) {
  logs.push({
    at: new Date().toISOString(),
    event
  });
}

async function getFeatureFlags() {
  const res = await fetch('https://flags.example.com/config.json');
  return res.json();
}

function renderDashboard(userId) {
  const stats = calculateAllStats(userId); // 重い処理
  return buildHtml(stats);
}

const fs = require('fs');

function handleRequest(req, res) {
  const content = fs.readFileSync('./template.html', 'utf8');
  res.end(content);
}

async function fetchWithRetry(url) {
  for (let i = 0; i < 2; i++) {
    try {
      const res = await fetch(url);
      if (!res.ok) throw new Error('bad status');
      return res;
    } catch (e) {
      await new Promise(r => setTimeout(r, 100));
    }
  }
  throw new Error('failed after 2 retries');
}

function handleClick() {
  let sum = 0;
  for (let i = 0; i < 1_000_000_000; i++) {
    sum += i;
  }
  alert(sum);
}

function calculate(pageSize) {
  return 1000 / pageSize;
}

async function fetchAll(urls) {
  const promises = urls.map(url => fetch(url));
  return Promise.all(promises);
}