JavaScript Questions & Answers – Object Attributes and Serialization

This set of Javascript Multiple Choice Questions & Answers (MCQs) focuses on “Object Attributes and Serialization”.

1. The unordered collection of properties, each of which has a name and a value is called
a) String
b) Object
c) Serialized Object
d) Array
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2. The object has three object attributes namely
a) Class, parameters, object’s extensible flag
b) Prototype, class, objects’ parameters
c) Prototype, class, object’s extensible flag
d) Native object, Classes and Interfaces and Object’s extensible flag
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3. Consider the following code snippet :

var book = {
              "main title": "JavaScript", 
              'sub-title': "The Definitive Guide", 
              "for": "all audiences", 
              author: { 
                         firstname: "David", 
                         surname: "Flanagan" 
                      }
           };

In the above snippet, firstname and surname are
a) properties
b) property values
c) property names
d) objects
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4. A linkage of series of prototype objects is called as ________
a) prototype stack
b) prototype chain
c) prototype class
d) prototypes
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5. In the following syntax, the datatype within the square brackets must be ___________

book[datatype]=assignment_value;

a) An integer
b) A String
c) An object
d) Floating point
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6. To determine whether one object is the prototype of (or is part of the prototype chain of) another object, one should use the ____________
a) isPrototypeOf() method
b) equals() method
c) === operator
d) ==opertor
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7. What is the prototype represents in the following code snippet?

function f() {};

a) Function f
b) A custom constructor
c) Prototype of a function
d) Not valid
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8. The purpose of extensible attribute is to __________
a) make all of the own properties of that object non configurable
b) to configure and bring a writable property
c) “lock down” objects into a known state and prevent outside tampering
d) to include new properties into the object
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9. Identify the process done in the below code snippet?

o = {x:1, y:{z:[false,null,""]}}; 
s = JSON.stringify(o); 
p = JSON.parse(s);

a) Object Encapsulation
b) Object Serialization
c) Object Abstraction
d) Object Encoding
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10. The basic purpose of the toLocaleString() is to _________
a) return a localised object representation
b) return a parsed string
c) return a local time in the string format
d) return a localized string representation of the object
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11. What will be the output of the following Javascript code?

const object1 = {};  
a = Symbol('a');  
b = Symbol.for('b');  
object1[a] = 'harry';  
object1[b] = 'derry';  
const objectSymbols = Object.getOwnPropertySymbols(object1);  
console.log(objectSymbols.length);

a) 0
b) 2
c) 1
d) Error
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12. What will be the output of the following Javascript code?

const obj1 =
{  
  		property1: 21  
}  
const descriptor1 = Object.getOwnPropertyDescriptor(obj1, 'property1');  
console.log(descriptor1.configurable);  
console.log(descriptor1.enumerable);

a) true 21
b) true false
c) true true
d) false false
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13. What will be the output of the following Javascript code?

const obj1 = { property1: '10'};  
const obj2 = Object.freeze(obj1);  
obj2.property1 = '20';  
console.log(obj2.property1);

a) 10
b) 20
c) Runtime error
d) Compilation error
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14. What will be the output of the following Javascript code?

const object1 = {  
  property1: 20
};  
console.log(Object.is(object1));

a) 20
b) true
c) false
d) error
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15. What will be the output of the following Javascript code?

const obj = {prop: 12};  
Object.preventExtensions(obj);  
console.log( Object.isExtensible(obj));

a) 12
b) false
c) true
d) error
View Answer

Sanfoundry Global Education & Learning Series – Javascript Programming.