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

Answer & Solution

Answer: Option A
Solution:
The for...in loop iterates over all enumerable properties of an object.
Related Questions on Average

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

A). var obj = {};

B). var obj = [];

C). var obj = ();

D). var obj = {};

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: () {}

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

A). 30

B). John

C). undefined

D). null

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';

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 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 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 can you delete the age property from the person object?

A). delete person.age;

B). remove person.age;

C). person.age = null;

D). person.age.delete;