Les closures sont super utiles ! Voici des cas concrets :

🏭 Factory pattern

function createValidator(rules) {
  return function(data) {
    return rules.every(rule => rule(data));
  };
}

const emailValidator = createValidator([
  data => data.includes('@'),
  data => data.length > 5
]);

🔒 Variables privées (avant les classes)

function createBankAccount(initialBalance) {
  let balance = initialBalance;
  
  return {
    deposit: (amount) => balance += amount,
    withdraw: (amount) => balance -= amount,
    getBalance: () => balance
  };
}

⚡ Throttle/Debounce

function debounce(func, delay) {
  let timeoutId;
  return function(...args) {
    clearTimeout(timeoutId);
    timeoutId = setTimeout(() => func.apply(this, args), delay);
  };
}

Les closures permettent de créer des "environnements persistants" ! 🧠