What is Object-oriented Programming (OOP)?

8. Complete Quizzes (100%) And Earn Points (3)- Javascript Questions & Answers (Q&A) – Classes in JavaScript

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   1. Question

   Q. What will be the output of the following Javascript code?

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

   console.log(object1.property1);

   0

   • 0
   • 10
   • undefined
   • error
   Correct
   

   Explanation: Object.defineProperties() is a predefined function in the object library of javascript. The Object.defineProperties() method defines new or modifies existing properties directly on an object and returns the object.

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   Explanation: Object.defineProperties() is a predefined function in the object library of javascript. The Object.defineProperties() method defines new or modifies existing properties directly on an object and returns the object.

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2. Question 2 of 3

   2. Question

   Q. What will be the output of the following Javascript code?

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

   0

   • true
   • false
   • error
   • 0
   Correct
   

   Explanation: The Object.getPrototypeOf() method of JavaScript returns the prototype value of the specified object. There are no inherited properties in this object.

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   Explanation: The Object.getPrototypeOf() method of JavaScript returns the prototype value of the specified object. There are no inherited properties in this object.

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3. Question 3 of 3

   3. Question

   Q. 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;

   0

   • 2
   • 4
   • Error
   • Undefined
   Correct
   

   Explanation: The seal property does not allow the object to be deleted. The object to be sealed is passed as an argument, and the method returns the object which has been sealed.

   0

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   Explanation: The seal property does not allow the object to be deleted. The object to be sealed is passed as an argument, and the method returns the object which has been sealed.

   0

Object-oriented programming (OOP) is a popular programming paradigm or style of programming. It’s been around since ‘70s, but unlike tools and frameworks that come and go, OOP is still very relevant today. That’s because it’s not a programming language or a tool. It’s a style of programming.

11. Complete Quizzes (100%) And Earn Points (3)- Java Questions & Answers (Q&A) – Relational Operators and Boolean Logic Operators

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   1. Question

   What will be the output of the following Java code?

   class bool_operator
   {
   public static void main(String args[])
   {
   boolean a = true;
   boolean b = !true;
   boolean c = a | b;
   boolean d = a & b;
   boolean e = d ? b : c;
   System.out.println(d + ” ” + e);
   }
   }

   0

   • false false
   • true ture
   • true false
   • false true
   Correct
   

   Explanation: Operator | returns true if any one operand is true, thus ‘c = true | false’ is true. Operator & returns a true if both of the operand is true thus d is false. Ternary operator ?: assigns left of ‘:’ if condition is true and right hand of ‘:’ if condition is false. d is false thus e = d ? b : c , assigns c to e , e contains true.
   output:
   $ javac bool_operator.java
   $ java bool_operator
   false true

   0

   Incorrect
   

   Explanation: Operator | returns true if any one operand is true, thus ‘c = true | false’ is true. Operator & returns a true if both of the operand is true thus d is false. Ternary operator ?: assigns left of ‘:’ if condition is true and right hand of ‘:’ if condition is false. d is false thus e = d ? b : c , assigns c to e , e contains true.
   output:
   $ javac bool_operator.java
   $ java bool_operator
   false true

   0
2. Question 2 of 3

   2. Question

   Q. What will be the output of the following Java code?

   class ternary_operator
   {
   public static void main(String args[])
   {
   int x = 3;
   int y = ~ x;
   int z;
   z = x > y ? x : y;
   System.out.print(z);
   }
   }

   0

   • 0
   • 1
   • 3
   • -4
   Correct
   

   Explanation: None.
   output:
   $ javac ternary_operator.java
   $ java ternary_operator
   3

   0

   Incorrect
   

   Explanation: None.
   output:
   $ javac ternary_operator.java
   $ java ternary_operator
   3

   0
3. Question 3 of 3

   3. Question

   Q. What will be the output of the following Java code?

   class Output
   {
   public static void main(String args[])
   {
   boolean a = true;
   boolean b = false;
   boolean c = a ^ b;
   System.out.println(!c);
   }
   }

   0

   • 0
   • 1
   • false
   • true
   Correct
   

   Explanation: None.
   output:
   $ javac Output.java
   $ java Output
   false

   0

   Incorrect
   

   Explanation: None.
   output:
   $ javac Output.java
   $ java Output
   false

   0

Why learn OOP?

OOP helps you manage and reduce complexity in software by building re-usable building blocks (objects). Properly designed objects provide a simple interface and hide the unnecessary complexity from the outside, just like a DVD player! A DVD player has a complex logic board on the inside and a few buttons on the outside. When you press the play button, you don’t care how all those microchips talk to each other.

Object-oriented programming helps you:

• Manage and reduce complexity
• Eliminate redundant code
• Build re-usable building blocks
• Write cleaner code

An essential skills for every developer

OOP comes up in many technical interviews. So if you really want to be a serious developer, you need to understand object-oriented programming. As a technical interviewer myself, if I see a candidate with OOP on their resume, that candidate stands out to me. 

It may interest you to know that many of the popular frameworks out there that you might be using are actually designed with OOP concepts in mind. Angular is an example of such frameworks! 

A Step-by-Step, A to Z course

What you’ll get when you sign up for this course:

• Learn all about object-oriented programming in JavaScript
• No more wasting time on disjointed tutorials
• Learn at your own pace – lifetime access – so take your time if you prefer
• Watch on any device, online or offline
• Solidify your understanding of JavaScript
• Prepare for technical interviews
• Confidently build applications with Node, Angular, React, Vue and other JavaScript libraries
• Learn the best practices and common pitfalls to avoid
• Certificate of completion to present to your employer

You’ll learn

• The core principles of OOP: encapsulation, abstraction, inheritance and polymorphism
• How to implement OOP concepts in JavaScript
• All about objects, their properties, property descriptors, getters and setters
• Difference between factory and constructor functions
• How “this” works in JavaScript
• Prototypes and prototypical inheritance: one of the confusing parts of JavaScript
• ES6+ features used in object-oriented programming

This course is for you if:

You’re a developer who already knows OOP principles but want to learn how to implement them in JavaScript.

You’re a developers who is not familiar with OOP, perhaps you just know the basics of JavaScript and want to solidify your understanding of JS and prepare for technical interviews.

Having OOP and JS on your resume helps you find more jobs and make more money.

Are you ready to take your JavaScript skills to the next level? Enroll in the course and get started.