Javascript Multiple Choice Questions and Answers Classes in JavaScript

(1) The behaviour of the instances present of a class inside a method is defined by __________

[A] Method

[B] Classes

[C] Interfaces

[D] Classes and Interfaces

Answer: Classes

(2) The keyword or the property that you use to refer to an object through which they were invoked is _________

[A] from

[B] to

[C] this

[D] object

Answer: this

(3) What will be the output of the following JavaScript code?

var o = new F();

o.constructor === F

[A] false

[B] true

[C] 0

[D] 1

Answer: true

(4) The basic difference between JavaScript and Java is _________

[A] There is no difference

[B] Functions are considered as fields

[C] Variables are specific

[D] Functions are values, and there is no hard distinction between methods and fields

Answer: Functions are values, and there is no hard distinction between methods and fields

(5) The meaning for Augmenting classes is that ___________

[A] objects inherit prototype properties even in a dynamic state

[B] objects inherit prototype properties only in a dynamic state

[C] objects inherit prototype properties in the static state

[D] object doesn’t inherit prototype properties in the static state

Answer: objects inherit prototype properties even in a dynamic state

(6) The property of JSON() method is __________

[A] it can be invoked manually as object.JSON()

[B] it will be automatically invoked by the compiler

[C] it is invoked automatically by the JSON.stringify() method

[D] it cannot be invoked in any form

Answer: it is invoked automatically by the JSON.stringify() method

(7) When a class B can extend another class A, we say that?

[A] A is the superclass and B is the subclass

[B] B is the superclass and A is the subclass

[C] Both A and B are the superclass

[D] Both A and B are the subclass

Answer: A is the superclass and B is the subclass

(8) If A is the superclass and B is the subclass, then subclass inheriting the superclass can be represented as _________

[A] B=inherit(A);

[B] B=A.inherit();

[C] B.prototype=inherit(A);

[D] B.prototype=inherit(A.prototype);

Answer: B.prototype=inherit(A);

(9) The snippet that filters the filtered set is __________

[A] var t=new FilteredSet(s, {function(s) {return !(x instanceof Set);});

[B] var t=new FilteredSet{function(s) {return !(x instanceof Set);});

[C] var t=new FilteredSet(s, {function(s) {return (x instanceof Set);});

[D] var t=new FilteredSet(s, {function(s) {return x;});

Answer: var t=new FilteredSet(s, {function(s) {return !(x instanceof Set);});

(10) The method that can be used to create new properties and also to modify the attributes of existing properties is _________

[A] Object.defineProperty()

[B] Object.defineProperties()

[C] Both Object.defineProperty() and Object.defineProperties()

[D] Object.inherit()

Answer: Both Object.defineProperty() and Object.defineProperties()

(11) What will be the output of the following JavaScript code?

const obj1 = 
{  
  	a: 10,  
  	b: 15,  
  	c: 18  
};  
const obj2 = Object.assign({c: 7, d: 1}, obj1);  
console.log(obj2.c, obj2.d);

[A] 7,1

[B] 18,1

[C] Undefined

[D] Error

Answer: 7,1

(12) What will be the output of the following JavaScript code?

function person()
{  
        this.name = 'rahul';  
}  
function obj() 
{  
       obj.call(this)  
}  
obj.prototype = Object.create(person.prototype);  
const app = new obj();  
console.log(app.name);

[A] undefined

[B] runtime error

[C] compilation error

[D] rahul

Answer: rahul

(13) What will be the output of the following JavaScript code?

const object1 = {};  
Object.defineProperties(object1,
{  
  	property1: 
        {  
             value: 10 
        }  
 });  
console.log(object1.property1);

[A] 0

[B] 10

[C] undefined

[D] error

Answer: 10

(14) What will be the output of the following JavaScript code?

const prototype1 = {};  
const object1 = Object.create(prototype1);  
console.log(Object.getPrototypeOf(object1) === prototype1);

[A] true

[B] false

[C] error

[D] 0

Answer: true

(15) What will be the output of the following JavaScript code?

const obj1 = {  
  property1: 2  
};  
Object.seal(object1);    
obj1.property1 =4;  
console.log(obj1.property1);  
delete obj1.property1;

[A] 2

[B] 4

[C] Error

[D] Undefined

Answer: Error

JavaScript Questions & Answers – Classes in JavaScript | JavaScript MCQs

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