Q
How can you iterate over all properties of an object?

Answer & Solution

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

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

A). Honda

B). Civic

C). Undefined

D). Error

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 class in JavaScript ES6?

A). class ClassName { constructor() {} }

B). function ClassName() { constructor() {} }

C). class ClassName() { constructor {} }

D). function class ClassName { constructor() {} }

Which method can be used to call a function defined within an object?

A). object.functionName();

B). object->functionName();

C). object::functionName();

D). object.callFunction('functionName');

How do you define a method in a constructor function?

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

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

C). this.methodName = () {}

D). this.methodName: () {}

In JavaScript, what keyword is used to define a new object from a constructor function?

A). create

B). construct

C). new

D). object

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 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

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