Quiz - Object Oriented Javascript

arunram.krish
Quiz by arunram.krish, updated more than 1 year ago
arunram.krish
Created by arunram.krish over 3 years ago
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Quiz on Object Oriented Javascript

Resource summary

Question 1

Question
What are the different ways in which you can create a javascript object? Choose ALL the right options
Answer
  • var object = { prop1: "value1", prop2 : "value2"};
  • var object = new Object();
  • var object = {};
  • var object = Object.create({});

Question 2

Question
How to create a constructor function?
Answer
  • Any function when prefixed with "new" keyword at the time of invocation acts like a constructor function.
  • Name of the function should be "constructor"
  • You have to assign a property named "constructor" and assign a function to it
  • Constructor function cannot be created in javascript

Question 3

Question
How do you demonstrate inheritance in Javascript? Consider "BaseClass" is the name of the parent class and "SubClass" is the name of the sub-class.
Answer
  • class SubClass extends BaseClass { }
  • function SubClass() { BaseClass.apply(this, Array.prototype.slice.call(arguments, 0); } SubClass.prototype = Object.create(BaseClass.prototype);
  • function SubClass() { BaseClass.apply(this, Array.prototype.slice.call(arguments, 0); }
  • function SubClass() { super(Array.prototype.slice.call(arguments, 0)); } SubClass.prototype = Object.create(BaseClass.prototype);

Question 4

Question
When does a Closure scope gets created?
Answer
  • Every function has a Closure scope associated with it
  • Every time a inner function is defined within another function
  • When an inner function is defined within another function and that refers to variables that are available at the defining function (local variables of enclosing functions and its parent right until global)
  • A closure keyword is available. When a variable is declared with that modifier, closure scope is created

Question 5

Question
How can I create a constant in Javascript 5?
Answer
  • const myConstant = 3.414;
  • var myConstant = { value : "3.414";}
  • var myConstant = new Object(3.414)
  • var myConstant = Object.create(null, { value: { configurable : false, writable : false, enumerable : false, value : 3.414 } });

Question 6

Question
How does Javascript achieve Inheritance?
Answer
  • Inheritance using extends keyword
  • Inheritance through Constructor chaining
  • Inheritance through Prototype chaining
  • Inheritance achieved programmatically

Question 7

Question
Javascript does not support overriding?
Answer
  • True
  • False

Question 8

Question
It is a better practice (in terms of performance) to create deep inheritance and access methods in the ancestor classes.
Answer
  • True
  • False

Question 9

Question
It is possible to create namespaces in Javascript.
Answer
  • True
  • False

Question 10

Question
It is possible to implement Singleton pattern in javascript.
Answer
  • True
  • False

Question 11

Question
Every Javascript function is an object with the constructor as "Function"
Answer
  • True
  • False

Question 12

Question
How can I create immutable property in a javascript object?
Answer
  • Using closure
  • Using JSON
  • Using Object.defineProperty and specify only get and no set function
  • By making the property private

Question 13

Question
How to ensure that a property in Javscript object is never removed or re-configured
Answer
  • Define the property with private modifier
  • It is not possible to stop removing the property from object
  • Every property defined using "Object.defineProperty" cannot be removed
  • Using Object.defineProperty and setting "configurable" to false

Question 14

Question
How can I avoid creating global variables and functions used most often for initialization?
Answer
  • Using temporary inner / anonymous function functions
  • Using just closure
  • Using constructor
  • Using window object

Question 15

Question
How can I create Block - scoped variable in ES-6?
Answer
  • Using var
  • Using let
  • Using const
  • Using def
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