Protected Members

Protected members are available inside a class and its subclasses, but not to outside callers.

protected.ts

class Account {
    protected cents: number;

    constructor(cents: number) {
        this.cents = cents;
    }
}

class SavingsAccount extends Account {
    addInterest(rate: number): void {
        const interest: number = this.cents * rate;
        this.cents = this.cents + interest;
    }

    balance(): number {
        return this.cents;
    }
}

const rate: number = ;
const account: SavingsAccount = new SavingsAccount(1000);
account.addInterest(rate);

console.log(`balance=${account.balance()}`);

class Account {
    protected cents: number;

    constructor(cents: number) {
        this.cents = cents;
    }
}

class SavingsAccount extends Account {
    addInterest(rate: number): void {
        const interest: number = this.cents * rate;
        this.cents = this.cents + interest;
    }

    balance(): number {
        return this.cents;
    }
}

const rate: number = ;
const account: SavingsAccount = new SavingsAccount(1000);
account.addInterest(rate);

console.log(`balance=${account.balance()}`);

class Account {
    protected cents: number;

    constructor(cents: number) {
        this.cents = cents;
    }
}

class SavingsAccount extends Account {
    addInterest(rate: number): void {
        const interest: number = this.cents * rate;
        this.cents = this.cents + interest;
    }

    balance(): number {
        return this.cents;
    }
}

const rate: number = ;
const account: SavingsAccount = new SavingsAccount(1000);
account.addInterest(rate);

console.log(`balance=${account.balance()}`);

protected `protected` marks a member that subclasses can use while ordinary callers cannot.