Classes And Modules MCQ question and answer in javascript with solution

11

The four kinds of class members are

A) Instance methods, Instance fields, Static method, Dynamic method B) Instance fields, Instance methods, Class fields, Class methods C) Instance fields, Non-instance fields, Dynamic methods, Global methods D) Global methods, Local methods, Dynamic methods, Static methods

Discuss

Answer & Solution

Answer: Option B

Solution:

The four kinds of class members are Instance fields, Instance methods, Class fields, Class methods.

12

The properties of the objects act like different kinds of class members. They are

A) Public object, Private object, Protected object B) Constructor object, Function object, Destructor object C) Constructor object, Prototype object, Instance object D) Instance method, Static object, Dynamic object

Discuss

Answer & Solution

Answer: Option C

Solution:

In JavaScript, there are three different objects involved inany class definition, and the properties of these three objects act like different kinds of class members namely, Constructor object, Prototype object, and Instance object.

13

The object whose properties are inherited by all instances of the class, and properties whose values are functions behaving like instance methods of the class, is

A) Instance object B) Constructor object C) Destructor object D) Prototype object

Discuss

Answer & Solution

Answer: Option D

Solution:

The properties of the prototype object are inhertied by all instances of the class, and properties whose values are functions behave like instance methods of the class.

14

Which are usually variables that are used internally in object methods and also are globally visible variables?

A) Object properties B) Variable properties C) Method properties D) Internal properties

Discuss

Answer & Solution

Answer: Option B

Solution:

The variable properties are usually variables that are used internally in the objects methods, but can also be globally visible variables that are used through the page.

15

The class that represents the regular expressions is

A) RegExpObj B) RegExpClass C) RegExp D) StringExp

Discuss

Answer & Solution

Answer: Option C

Solution:

The JavaScript RegExp class represents regular expressions, and both string and RegExp define methods that use regular expressions.

16

Which is the correct code that returns a complex number that is the complex conjugate of this one?

A) Complex.prototype.conj = function() { return new Complex(this.r, -this.i); }; B) Complex.prototype.conj = function() { return Complex(this.r, -this.i); }; C) Complex.prototype.conj = function() { return (this.r, -this.i); }; D) Complex.prototype.conj = function() { new Complex(this.r, -this.i); };

Discuss

Answer & Solution

Answer: Option A

Solution:

The above code snippet returns a complex number that is the complex conjugate of this one.

17

How can we make methods available on all objects?

A) Object.add(methods) B) Object.methods(add) C) Object.add.methods(…) D) Object.prototype

Discuss

Answer & Solution

Answer: Option D

Solution:

It is possible to add methods to Object.prototype, making them available on all objects. This is not recommended, however, because prior to ECMAScript5, there is no way to make these add-on methods nonenumerable, and if you add properties to Object.prototype, those properties will be reported by all for/in loops.

18

What is the procedure to add methods to HTMLElement so that they will be inherited by the objects that represent the HTML tags in the current document?

A) HTMLElement.prototype(…) B) HTMLElement.prototype C) HTML.addmethods() D) HTML.elements(add)

Discuss

Answer & Solution

Answer: Option B

Solution:

It is implementation-dependent whether classes defined by the host environment (such as the web browser) can be augmented using Object.prototype. In many web browsers, for example, you can add methods to HTMLElement.prototype and those methods will be inherited by the objects that represent the HTML tags in the current document.

19

You can refresh the webpage in JavaScript by using

A) window.reload B) location.reload C) window.refresh D) page.refresh

Discuss

Answer & Solution

Answer: Option B

Solution:

One can refresh the webpage in JavaScript by using location.reload.

20

The functions provide() and require() of Dojo toolkit and Google’s Closure library are used for

A) declaring and loading modules B) loading and declaring modules C) declaring modules D) none of the mentioned

Discuss

Answer & Solution

Answer: Option A

Solution:

Both the Dojo toolkit and Google’s Closure library define provide() and require() functions for declaring and loading modules.