tarnsation.js

function makeid(length) {
    var result           = '';
    var characters       = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789';
    var charactersLength = characters.length;
    for ( var i = 0; i < length; i++ ) {
       result += characters.charAt(Math.floor(Math.random() * charactersLength));
    }
    return result;
}

class Tarnsation {
    constructor(account_id, qty) {
        this.account_id = account_id;
        this.qty = qty;
        this.timestame = new Date();
    }
}

class Account {
    constructor(transactions) {
        this.id = makeid(20);
        this.balance = 0;

        transactions.push(new Tarnsation(this.id, 10000));
        this.updateBalance();
    }
    send(account, qty) {
        this.updateBalance();
        if (qty > this.balance) {
            console.log('ยอดโอนสูงกว่าทีมมีอยู่');
            return false;
        }

        transactions.push(new Tarnsation(this.id, qty *-1));
        this.updateBalance();
    
        transactions.push(new Tarnsation(account.id, qty));
        account.updateBalance();
    }
    updateBalance () {
        let value = 0;
        transactions
            .filter((tarnsation) => tarnsation.account_id == this.id)
            .forEach((tarnsation) => { value += tarnsation.qty; });
        this.balance = value;
    }
}

const transactions = [];

const mark = new Account(transactions);
console.log(mark);

const mark2 = new Account(transactions);
console.log(mark2);

mark.send(mark2, 1000000)
mark.send(mark2, 500)
console.log(transactions);
console.log(mark);
console.log(mark2);