Q
What will the following code output? console.log(person['age']); if var person = {name: 'John'};

Answer & Solution

Answer: Option C
Solution:
Accessing a non-existing property of an object returns undefined.
Related Questions on Average

What will console.log(newCar.make); output if class Car { constructor(make) { this.make = make; }} var newCar = new Car('Honda');?

A). Honda

B). Car

C). Undefined

D). Error

What will console.log(car.make); output if var car = {make: 'Toyota', model: 'Corolla'};?

A). Toyota

B). Corolla

C). Undefined

D). Error

How do you add a new property gender with value male to the person object?

A). person.gender = 'male';

B). person.gender = male;

C). person.gender = ['male'];

D). person[gender] = 'male';

What is the purpose of the this keyword in a constructor function?

A). It refers to the new object being created.

B). It refers to the global object.

C). It refers to the current object.

D). It refers to the parent object.

How do you create an instance of the Car object using the constructor function?

A). var myCar = new Car('Toyota', 'Corolla');

B). var myCar = Car('Toyota', 'Corolla');

C). var myCar = create Car('Toyota', 'Corolla');

D). var myCar = construct Car('Toyota', 'Corolla');

How do you iterate over all properties of an object var person = {name: 'John', age: 30};?

A). for (var key in person)

B). for (var key of person)

C). forEach(key in person)

D). forEach(key of person)

How do you access the value of the name property in the object var person = {name: 'John', age: 30};?

A). person['name']

B). person.name

C). person->name

D). person::name

How do you call a method from a parent class in a subclass in JavaScript ES6?

A). super.methodName()

B). this.methodName()

C). parent.methodName()

D). base.methodName()

How do you define a method named greet in an object var person = {};?

A). person.greet = function() {};

B). person.greet: function() {};

C). person.greet = () {};

D). person.greet = function {};

How do you add a method to an object created with a constructor function?

A). this.methodName = function() {}

B). this.methodName: function() {}

C). this.methodName = () {}

D). this.methodName: () {}