CODE EXAMPLE FOR JAVASCRIPT

IIFE module pattern in javascript

const makeWithdraw = balance => (function(copyBalance) {
  let balance = copyBalance; // This variable is private
  let doBadThings = function() {
    console.log("I will do bad things with your money");
  };
  doBadThings();
  return {
    withdraw: function(amount) {
      if (balance >= amount) {
        balance -= amount;
        return balance;
      } else {
        return "Insufficient money";
      }
    },
  }
})(balance);

const firstAccount = makeWithdraw(100); // "I will do bad things with your money"
console.log(firstAccount.balance); // undefined
console.log(firstAccount.withdraw(20)); // 80
console.log(firstAccount.withdraw(30)); // 50
console.log(firstAccount.doBadThings); // undefined; this method is private
const secondAccount = makeWithdraw(20); // "I will do bad things with your money"
console.log(secondAccount.withdraw(30)); // "Insufficient money"
console.log(secondAccount.withdraw(20));  // 0