How do you add a new property to an existing object in JavaScript?

How can you check if a property exists in an object?

A). 'property' in object

B). object.hasProperty('property')

C). object.contains('property')

D). object.includes('property')

Which of the following is the correct way to delete a property from an object?

A). remove object.property;

B). delete object.property;

C). delete object[property];

D). object.property = null;

What does Object.keys(obj) return?

A). An array of the values of the object's properties

B). An array of the names of the object's properties

C). The first key of the object

D). The number of properties in the object

How do you define a constructor function for a Car object?

A). function Car(make, model, year) { this.make = make; this.model = model; this.year = year; }

B). Car(make, model, year) { this.make = make; this.model = model; this.year = year; }

C). function create Car(make, model, year) { this.make = make; this.model = model; this.year = year; }

D). function construct Car(make, model, year) { this.make = make; this.model = model; this.year = year; }

How do you define a method inside a class in JavaScript ES6?

A). methodName() {}

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

C). function methodName() {}

D). methodName: function() {}

What will car['make'] return if var car = {make: 'Ford', model: 'Mustang'};?

A). Ford

B). Mustang

C). Undefined

D). Error

What is the purpose of the this keyword in an object method?

A). It refers to the global object.

B). It refers to the current object.

C). It refers to the parent object.

D). It refers to the previous object.

What is encapsulation in the context of JavaScript objects?

A). Hiding the internal state and requiring all interaction to be performed through an object's methods

B). Extending one object from another

C). Creating a new object

D). Removing a property from an object

Which of the following correctly creates an instance of a Car object using a constructor function?

A). var myCar = Car('Toyota', 'Corolla', 2020);

B). var myCar = new Car('Toyota', 'Corolla', 2020);

C). var myCar = create Car('Toyota', 'Corolla', 2020);

D). var myCar = construct Car('Toyota', 'Corolla', 2020);

What will the following code output? console.log(car.make); if var car = {make: 'Honda', model: 'Civic'};

A). Honda

B). Civic

C). Undefined

D). Error