Javascript (JS) Custom Objects MCQ

This section focuses on the "Javascript Custom Objects" of the Javascript. These Multiple Choice Questions (mcq) should be practiced to improve the Javascript skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

1. What will be the output of the below code?
class Rect {
constructor(h, w) {
this.height = h;
this.width = w;
}
get foo() {
return this.foo();
}
foo() {
return this.height * this.width;
}
}

const sq = new Rect(5, 20);
console.log(sq.foo());


A. this.height * this.width
B. 100
C. Reference Error
D. 5*20

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2. Choose the correct syntax in order to access property of the object created?
function Ticket(from,to,pName){
this.from=from;
this.to=to;
this.pName= pName;
}

var ticket=new Ticket( "Udaipur","Pune","Raj" );


A. ticket.from & ticket[to]
B. ticket[to] & ticket[from]
C. ticket {to} & ticket.to
D. ticket[to] & ticket{from}

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3. Identify the correct syntax to create a JavaScript object for Employee with property empid, empName?
function Ticket(from,to,pName){
this.from=from;
this.to=to;
this.pName= pName;
}

var ticket=new Ticket( "Udaipur","Pune","Raj" );


A. var employee=new Object(); employee.empid=20; employee.empName="John";
B. var employee ={id:2001,empName:"John"};
C. var employee=Employee(); employee.empid=20; employee.empName="John";
D. Both A and C

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4. Consider the below code:
Choose the appropriate statement to be inserted at line 2, in order to create a JavaScript object named student?
var json= '{ "sId":2001,"sName":"John" }';
//line 2
console.log(student.sId+" "+student.sName);


A. var student=json.parse(json);
B. var student=JSON.stringify(json);
C. var student=JSON.parse(json);
D. var student=json.stringify(json);

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5. What will be the output of the following JavaScript code?
var obj = new Fun(); obj.constructor === Fun

A. true
B. false
C. 0
D. 1

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6. If X is the superclass and Y is the subclass, then subclass inheriting the superclass can be represented as _________

A. Y=inherit(X);
B. Y=X.inherit();
C. Y.prototype=inherit(X);
D. Y.prototype=inherit(X.prototype);

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7. What will be the output of the following JavaScript code?
const ob1 = { a: 5, b: 10, c: 15 }; const ob2 = Object.assign({c: 8, d: 3}, ob1); console.log(ob2.c, ob2.d);

A. 8,3
B. 15,3
C. undefined
D. error

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8. What will be the output of the following JavaScript code?
const pt1 = {};
const ob1 = Object.create(pt1);
console.log( Object.getPrototypeOf(ob1) === pt1 );


A. true
B. false
C. errot
D. 0

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9. 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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10. Which is an equivalent code to invoke a function m of class o that expects two arguments x and y?

A. o(x,y);
B. o.m(x) && o.m(y);
C. m(x,y);
D. o.m(x,y);

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