2-undo.js

'use strict';

class AccountCommand {
  constructor(account, amount) {
    this.account = account;
    this.amount = amount;
  }

  execute() {
    throw new Error('Command.execute() is not implemented');
  }

  undo() {
    throw new Error('Command.undo() is not implemented');
  }
}

class Withdraw extends AccountCommand {
  execute() {
    this.account.balance -= this.amount;
  }

  undo() {
    this.account.balance += this.amount;
  }
}

class Income extends AccountCommand {
  execute() {
    this.account.balance += this.amount;
  }

  undo() {
    this.account.balance -= this.amount;
  }
}

class BankAccount {
  constructor(name) {
    this.name = name;
    this.balance = 0;
  }
}

class Bank {
  constructor() {
    this.commands = [];
  }

  operation(account, value) {
    const Command = value < 0 ? Withdraw : Income;
    const command = new Command(account, Math.abs(value));
    command.execute();
    this.commands.push(command);
  }

  undo(count) {
    for (let i = 0; i < count; i++) {
      const command = this.commands.pop();
      command.undo();
    }
  }

  showOperations() {
    const output = [];
    for (const command of this.commands) {
      output.push({
        operation: command.constructor.name.toLowerCase(),
        account: command.account.name,
        amount: command.amount,
      });
    }
    console.table(output);
  }
}

// Usage

const bank = new Bank();
const account1 = new BankAccount('Marcus Aurelius');
bank.operation(account1, 1000);
bank.operation(account1, -50);
const account2 = new BankAccount('Antoninus Pius');
bank.operation(account2, 500);
bank.operation(account2, -100);
bank.operation(account2, 150);
bank.showOperations();
console.table([account1, account2]);
bank.undo(2);
bank.showOperations();
console.table([account1, account2]);