js exercise bank account constructor functions and prototypes solution

1function Account(name, balance) {
2  this.name = name;
3  this.balance = balance;
4}
5
6Account.prototype.deposit = function(amount) {
7  if (this._isPositive(amount)) {
8    this.balance += amount;
9    console.info(`Deposit: ${this.name} new balance is ${this.balance}`);
10    return true;
11  }
12  return false;
13}
14
15Account.prototype.withdraw = function(amount) {
16  if (this._isAllowed(amount)) {
17    this.balance -= amount;
18    console.info(`Withdraw: ${this.name} new balance is ${this.balance}`);
19    return true;
20  }
21  return false;
22}
23
24Account.prototype.transfer = function(amount, account) {
25  if (this.withdraw(amount) && account.deposit(amount)) {
26    console.info(`Transfer: ${amount} has been moved from ${this.name} to ${account.name}`);
27    return true;
28  }
29  return false;
30}
31
32
33Account.prototype._isPositive = function(amount) {
34  const isPositive = amount > 0;
35  if (!isPositive) {
36    console.error('Amount must be positive!');
37    return false;
38  }
39  return true;
40}
41
42Account.prototype._isAllowed = function(amount) {
43  if (!this._isPositive(amount)) return false;
44
45  const isAllowed = this.balance - amount >= 0;
46  if (!isAllowed) {
47    console.error('You have insufficent funds!');
48    return false;
49  }
50  return true;
51}
52
53const a = new Account('a', 100);
54const b = new Account('b', 0);
55
56
57output.innerText += `before:  a: ${a.balance}, b: ${b.balance}\n`;
58
59a.transfer(100, b);
60
61output.innerText += `after:  a: ${a.balance}, b: ${b.balance}\n`;