OOP Design & Patterns

Preview — 3 of 10 questions

In which case will calling super cause an error in a subclass?

javascript

class Parent {
  constructor(name) {
    this.name = name;
  }
}

class Child extends Parent {
  constructor(name) {
    this.age = 10; // ReferenceError: Must call super before accessing 'this'
    super(name);
  }
}

AWhen super() is called after using this

BWhen the parent class has no constructor

CWhen super.method() is called, but the method does not exist in the parent class

DWhen super() is called inside a static method

What will be the output of the following code?

javascript

function Parent() {}
Parent.prototype.greet = function () {
  return "Hello";
};

function Child() {}
Child.prototype = Parent.prototype;

const instance = new Child();
console.log(instance.greet());

A"Hello"

BTypeError: instance.greet is not a function

Cundefined

DReferenceError: Parent is not defined

Given the following class, what is the correct output order?

javascript

class A {
  x = console.log("A property");
  constructor() {
    console.log("A constructor");
  }
}

class B extends A {
  y = console.log("B property");
  constructor() {
    super();
    console.log("B constructor");
  }
}

new B();

A"A constructor" → "B constructor" → "A property" → "B property"

B"A property" → "A constructor" → "B property" → "B constructor"

C"A property" → "B property" → "A constructor" → "B constructor"

D"A constructor" → "A property" → "B constructor" → "B property"

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