Access modifiers public private protected in Typescript - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the public access modifier mean in TypeScript?

The public modifier means the property or method can be accessed from anywhere: inside the class, subclasses, and outside the class.

beginner

What is the effect of the private access modifier in TypeScript?

The <strong>private</strong> modifier restricts access to the property or method only within the class where it is declared. It cannot be accessed from outside or subclasses.

beginner

How does the protected access modifier work in TypeScript?

The <strong>protected</strong> modifier allows access to the property or method inside the class and its subclasses, but not from outside these classes.

intermediate

Consider this TypeScript code snippet:<br><pre>class Animal {
  protected name: string;
  constructor(name: string) {
    this.name = name;
  }
}
class Dog extends Animal {
  public bark() {
    console.log(`${this.name} barks`);
  }
}</pre><br>Why can <code>this.name</code> be accessed inside <code>bark()</code>?

Because <code>name</code> is <strong>protected</strong>, it can be accessed inside the subclass <code>Dog</code>. Protected members are accessible in the class and its subclasses.

intermediate

What happens if you try to access a <strong>private</strong> property from a subclass in TypeScript?

You get a compile-time error because <strong>private</strong> properties are only accessible within the class they are declared in, not in subclasses.

Which access modifier allows a property to be accessed anywhere, including outside the class?

A protected

B private

C public

D readonly

The public modifier allows access from anywhere.

If a property is marked as private, where can it be accessed?

A Only inside the class it is declared

B Inside the class and subclasses

C Anywhere in the program

D Only outside the class

Private properties are only accessible inside their own class.

Which access modifier allows access in the class and its subclasses but not outside?

A private

B protected

C public

D static

Protected members are accessible in the class and subclasses only.

What will happen if you try to access a protected property from outside the class hierarchy?

A It will work fine

B It will be undefined

C Runtime error

D Compile-time error

Accessing protected members outside the class or subclasses causes a compile-time error.

Which of these is NOT an access modifier in TypeScript?

A external

B private

C public

D protected

'external' is not a valid access modifier in TypeScript.

Explain the differences between public, private, and protected access modifiers in TypeScript.

Think about who can see or use the property or method.

Describe a real-life example where you might use each access modifier in a TypeScript class.

Imagine a company with public services, private offices, and protected areas for managers.