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. What will be the firstname and surname of the following JavaScript code?

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

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 data type 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 JavaScript 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 following JavaScript 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
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Sanfoundry Global Education & Learning Series – Javascript Programming.