Q
How can you check if the age property exists in the person object?

Answer & Solution

Answer: Option D
Solution:
person.hasOwnProperty('age') checks if age is a direct property of person.
Related Questions on Average

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';

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

A). methodName() {}

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

C). function methodName() {}

D). methodName: function() {}

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()

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What is the output of console.log(person.greet()); if var person = {greet: function() {return 'Hello';}};?

A). Hello

B). Undefined

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

A). 30

B). John

C). undefined

D). null

What does Object.keys(person) return if var person = {name: 'John', age: 30};?

A). ['name', 'age']

B). ['John', 30]

C). {'name', 'age'}

D). {'John', 30}

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

A). Toyota

B). Corolla

C). Undefined

D). Error

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

A). Honda

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D). Error

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.

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D). It refers to the parent object.

What is the correct way to create an object in JavaScript?

A). var obj = {};

B). var obj = [];

C). var obj = ();

D). var obj = <>;