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JavaScript Questions & Answers – Functions and Functional Programming | JavaScript MCQs

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Free download in PDF JavaScript Multiple Choice Questions and Answers for competitive exams. These short objective type questions with answers are very important for Board exams as well as competitive exams like UPSC, NDA, SSC etc. These short solved questions or quizzes are provided by Gkseries./p>

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(1) What will be the output of the following JavaScript statement?

var grand_Total=eval("10*10+5");

[A] 10*10+5
[B] 105 as a string
[C] 105 as an integer value
[D] Exception is thrown
Answer: 105 as an integer value
(2) Do functions in JavaScript necessarily return a value?
[A] It is mandatory
[B] Not necessary
[C] Few functions return values by default
[D] some functions do not return any value
Answer: Few functions return values by default

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(3) Will the following JavaScript code work?

var tensquared = (function(x) {return x*x;}(10));

[A] Yes, perfectly
[B] Error
[C] Exception will be thrown
[D] Memory leak
Answer: Yes, perfectly
(4) What will be the output of the following JavaScript code?

var string2Num=parseInt("123xyz");

[A] 123
[B] 123xyz
[C] Exception
[D] NaN
Answer: 123
(5) The one-liner code that concatenates all strings passed into a function is ____________
[A] 
function concatenate()
   {
       return String.prototype.concat('', arguments);
   }
[B] 
 function concatenate()
 {
       return String.prototype.apply('', arguments);
  }
[C] 
function concatenate()
  {
       return String.concat.apply('', arguments);
  }
[D] 
function concatenate()
  {
      return String.prototype.concat.apply('', arguments);
   }
Answer: 
function concatenate()
  {
      return String.prototype.concat.apply('', arguments);
   }
(6) If you have a function f and an object o, you can define a method named m of o with ________
[A] o.m=m.f;
[B] o.m=f;
[C] o=f.m;
[D] o=f;
Answer: o.m=f;
(7) What will be the equivalent statement of the following JavaScript statement?

var o = new Object();

[A] var o = Object();
[B] var o;
[C] var o= new Object;
[D] Object o=new Object();
Answer: var o= new Object;
(8) What is the difference between the two lines in the following JavaScript code?

!!(obj1 && obj2);

(obj1 && obj2);

[A] Both the lines result in a boolean value “True”
[B] Both the lines result in a boolean value “False”
[C] Both the lines check just for the existence of the object alone
[D] The first line results in a real boolean value whereas the second line merely checks for the existence of the objects
Answer: The first line results in a real boolean value whereas the second line merely checks for the existence of the objects
(9) What will be the state stored in d in the following JavaScript code? 
var c = counter(), d = counter();
c.count()
d.count()
c.reset()
c.count()
d.count()
[A] 1
[B] 0
[C] Null
[D] Undefined
Answer: 1
(10) What will be the last statement return in the following JavaScript code? 
function constfuncs()
{
   var funcs = [];
    for(var i = 0; i < 10; i++)
        funcs[i] = function() { return i; };
    return funcs;
}
var funcs = constfuncs();
funcs[5]()
[A] 9
[B] 0
[C] 10
[D] 12
Answer: 10
(11) What will be the output of the following JavaScript code? 
var arr = [7, 5, 9, 1];
var min = Math.min.apply(null, arr);
document.writeln(min);
[A] 7
[B] 5
[C] 1
[D] 9
Answer: 1
(12) What will be the output of the following JavaScript code? 
var add=new Function("num1","num2","return num1+num2");
document.writeln(add(2,5));
[A] 2
[B] 5
[C] Error
[D] 7
Answer: 7
(13) What will be the output of the following JavaScript code? 
var a=3.7;
var b=2;
a=ciel(a)
document.writeIn(a*b);
[A] 6
[B] 7.4
[C] 7.5
[D] 8
Answer: 8
(14) What will be the output of the following JavaScript code? 
var a=2.99;
var ans=floor(a)*floor(a)
console.log(ans);
[A] 9
[B] 8.31
[C] Error
[D] 4
Answer: 4
(15) What will be the output of the following JavaScript code? 
var a=225;
document.writeln(Math.sqrt(a));
[A] 225
[B] 15
[C] Error
[D] Undefined
Answer: 15

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