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

Questions
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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