JavaScript Classes — Quiz

What does a class declaration bind to its name?

A class constructor value Only a prototype object A source-code string A browser DOM node

What does a class expression evaluate to?

A class value A prototype chain array An instance automatically A module namespace

What role does a constructor method normally have in a base class?

Initialize the newly constructed instance Install methods on Object.prototype Run only when the class is imported Create a global variable

Where is an ordinary class instance method defined?

On the class prototype As a separate function on every instance Only inside the constructor On the global object

What strictness applies to code inside a class definition?

It is always strict mode code It depends on the surrounding script Only the constructor is strict Only private methods are strict

What does an instance field create?

State initialized separately for each instance A single shared property on the prototype A static property on the class A module-level binding

Can an instance field initializer use an earlier field through this?

Yes, instance fields are initialized in class element order No, fields cannot read this Only static fields can use this Only private fields can use earlier fields

Where is a static field or method associated?

With the class constructor value With every instance Only with the class prototype With Object.prototype

What relationship does extends establish?

A superclass relationship connecting the derived prototype to the base prototype A module import relationship A copy of all base instances A private field relationship

Why must a derived constructor call super() before accessing this?

super() initializes the derived instance before this can be used super() creates the global object super() copies methods into the instance super() is required only for static fields

When super.speak() is called from Dog.prototype.speak(), what is this inside the inherited method?

The current Dog instance Animal.prototype The Animal class constructor undefined

How is a private field accessed from class code?

With private-name syntax such as this.#balance With this["#balance"] With this.balance With Wallet.prototype.#balance from any code

Which statement describes a private method such as #read?

It is accessible only through the class private-name mechanism It is a public method whose name happens to start with # It is installed as an enumerable property It can be called as object["#read"]

What does #value in object test inside the class that declares #value?

Whether that object has the declaring class private element Whether object has a public property named "#value" Whether object is an instance of Object Whether value is enumerable

When do static initialization blocks execute?

During class evaluation, in class element order Only after the first instance is created Every time a static method runs When garbage collection occurs

Where does a static private element belong?

To the class value that declares it To every instance To the superclass prototype only To the global object

JavaScript Classes — Quiz