double-entry accounting

double-entry-accounting.ts

class Account {
  // The name of the account
  name: string;

  // The type of the account (e.g. asset, liability, etc.)
  type: string;

  // The balance of the account
  balance: number;

  // Constructor that sets the name and type of the account
  constructor(name: string, type: string) {
    this.name = name;
    this.type = type;
    this.balance = 0;
  }

  // Method that debits the account by the specified amount
  debit(amount: number) {
    this.balance -= amount;
  }

  // Method that credits the account by the specified amount
  credit(amount: number) {
    this.balance += amount;
  }
}

class Transaction {
  // The date of the transaction
  date: Date;

  // The accounts involved in the transaction
  accounts: Account[];

  // The amounts debited and credited for each account
  amounts: number[];

  // Constructor that sets the date and accounts involved in the transaction
  constructor(date: Date, accounts: Account[]) {
    this.date = date;
    this.accounts = accounts;
    this.amounts = new Array(accounts.length).fill(0);
  }

  // Method that sets the amount debited or credited for a specific account
  setAmount(account: Account, amount: number) {
    const index = this.accounts.indexOf(account);
    this.amounts[index] = amount;
  }

  // Method that records the transaction in the accounts
  record() {
    this.accounts.forEach((account, index) => {
      if (this.amounts[index] < 0) {
        account.debit(-this.amounts[index]);
      } else {
        account.credit(this.amounts[index]);
      }
    });
  }
}

// Create some accounts
const cash = new Account('Cash', 'asset');
const accountsReceivable = new Account('Accounts Receivable', 'asset');
const revenue = new Account('Revenue', 'income');

// Create a transaction and set the amounts for each account
const transaction = new Transaction(new Date(), [cash, accountsReceivable, revenue]);
transaction.setAmount(cash, 100);
transaction.setAmount(accountsReceivable, -100);
transaction.setAmount(revenue, 100);

// Record the transaction in the accounts
transaction.record();

// Print the balances of the accounts
console.log(cash.balance); // 100
console.log(accountsReceivable.balance); // -100
console.log(revenue.balance); // 100