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JavaScript 1000+ MCQ with answer for NDA

Thursday 9th of March 2023

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Downlaod JavaScript MCQ PDF
1. Consider the following code snippet :
var grand_Total=eval(10*10+5);

The output for the above statement would be :
A. 10*10+5
B. 105 as a string
C. 105 as an integer value
D. Exception is thrown
Answer : C
2. Which of the operator is used to test if a particular property exists or not?
A. in
B. exist
C. within
D. exists
Answer : A
3. What will be the output of the following JavaScript code?
var values=[one,two,Three];
var ans=values.shift();
document.writeln(ans);
A. one
B. two
C. three
D. error
Answer : A
4. Which of the following is not considered as an error in JavaScript?
A. Syntax error
B. Missing of semicolons
C. Division by zero
D. Missing of Bracket
Answer : C
5. What will be the output of the following JavaScript code?
var grade='B';
var result;
switch(grade)
{
case 'A':
{
result+=10;
break;
}
case 'B':
{
result+= 9;
break;
}
case 'C':
{
result+= 8;
break;
}
default:
result+= 0;
}
document.write(result);
A. 10
B. 9
C. 8
D. 0
Answer : B
6. What will be the output of the following JavaScript code?
var values=[1,2,3,4]
var ans=values.slice(1);
document.writeln(ans);
A. 1, 2, 3, 4
B. 2, 3, 4
C. 1, 3, 4
D. error
Answer : D
7. The statement a===b refers to _________
A. Both a and b are equal in value, type and reference address
B. Both a and b are equal in value
C. Both a and b are equal in value and type
D. There is no such statement
Answer : C
8. What will the following code snippet work? If not, what will be the error?
function tail(o)
{
for (; o.next; o = o.next) ;
return o;
}
A. No, this will throw an exception as only numerics can be used in a for loop
B. No, this will not iterate
C. Yes, this will work
D. No, this will result in a runtime error with the message Cannot use Linked List
Answer : C
9. A function definition expression can be called as __________
A. Function prototype
B. Function literal
C. Function calling
D. Function declaration
Answer : B
10. What will be the output of the following JavaScript code?
A. 7.25
B. -7.25
C. 7
D. -7
Answer : A
11. What will be the output of the following Javascript code?
<script>
var x = 5;
var y = 2;
var z = x % y;
document.getElementById("demo").innerHTML = z;
</script>
A. 0
B. 1
C. 2
D. 5
Answer : B
12. What will be the output of the following Javascript code?
<script>
var x = 10;
x *= 5;
document.getElementById("demo").innerHTML = x;
</script>
A. 5
B. 10
C. 50
D. Error
Answer : C
13. The main purpose of a Live Wire in NetScape is to ________
A. Create linkage between client side and server side
B. Permit server side, JavaScript code, to connect to RDBMS
C. Support only non relational database
D. To interpret JavaScript code
Answer : B
14. What will be the shift() output of the following JavaScript code?
var a = [];
a.unshift(1);
a.unshift(22);
a.shift();
a.unshift(3,[4,5]);
a.shift();
a.shift();
a.shift();
A. 1
B. [4,5]
C. [3,4,5]
D. Exception is thrown
Answer : A
15. What is the difference between the two lines given below ?
!!(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 checks 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 : D
16. 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 : D
17. The enumeration order becomes implementation dependent and non-interoperable if __________
A. If the object inherits enumerable properties
B. The object does not have the properties present in the integer array indices
C. The delete keyword is never used
D. Object.defineProperty() is not used
Answer : A
18. What will be the output of the following JavaScript code?
var val1=[1,2,3];
var val2=[6,7,8];
var result=val1.concat(val2);
document.writeln(result);
A. 1, 2, 3
B. Error
C. 1, 2, 3, 6, 7, 8
D. 123
Answer : C
19. What will be the output of the following JavaScript code?
function equalto()
{
int num=10;
if(num===10)
return true;
else
return false;
}
A. true
B. false
C. runtime error
D. compilation error
Answer : A
20. Which is a more efficient JavaScript code snippet?
Code 1 :
for(var num=10;num>=1;num--)
{
document.writeln(num);
}

Code 2 :
var num=10;
while(num>=1)
{
document.writeln(num);
num++;
}
A. Code 1
B. Code 2
C. Both Code 1 and Code 2
D. Cannot Compare
Answer : A
21. The primary purpose of the array map() function is that it __________
A. maps the elements of another array into itself
B. passes each element of the array and returns the necessary mapped elements
C. passes each element of the array on which it is invoked to the function you specify, and returns an array containing the values returned by that function
D. pass the elements of the array into another array
Answer : C
22. What will be the output of the following JavaScript code?
var a=5 , b=1
var obj = { a : 10 }
with(obj)
{
alert(b)
}
A. 10
B. Error
C. 1
D. 5
Answer : C
23. The function definitions in JavaScript begins with _____________
A. Identifier and Parentheses
B. Return type and Identifier
C. Return type, Function keyword, Identifier and Parentheses
D. Identifier and Return type
Answer : C
24. Among the following, which one is a ternary operator?
A. +
B. :
C. ^
D. ?:
Answer : D
25. What is the observation made in the following JavaScript code?
if (!a[i]) continue;
A. Skips the defined elements
B. Skips the existent elements
C. Skips the null elements
D. Skips the defined & existent elements
Answer : C
26. Which of the following Attribute is used to include External JS code inside your HTML Document?
A. src
B. ext
C. script
D. link
Answer : A
27. JavaScript _________ when there is an indefinite or an infinite value during an arithmetic computation.
A. Prints an exception error
B. Prints an overflow error
C. Displays Infinity
D. Prints the value as such
Answer : C
28. What is a block statement in JavaScript?
A. conditional block
B. block that contains a single statement
C. both conditional block and a single statement
D. block that combines multiple statements into a single compound statement
Answer : D
29. 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
Answer : A
30. What will be the output of the following JavaScript code?
var a1 = [,,,];
var a2 = new Array(3);
0 in a1
0 in a2
A. true false
B. false true
C. true true
D. false true
Answer : A
31. The property of a primary expression is ____________
A. stand-alone expressions
B. basic expressions containing all necessary functions
C. contains variable references alone
D. contains only keywords
Answer : A
32. What will be the output of the following JavaScript code?
Int a=1;
if(a>10)
{
document.write(10);
}
else
{
document.write(a);
}
A. 10
B. 0
C. 1
D. Undefined
Answer : C
33. 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
Answer : C
34. The snippet that has to be used to check if a is not equal to null is _________
A. if(a!=null)
B. if (!a)
C. if(a!null)
D. if(a!==null)
Answer : D
35. When does the function name become optional in JavaScript?
A. When the function is defined as a looping statement
B. When the function is defined as expressions
C. When the function is predefined
D. when the function is called
Answer : B
36. What will be the output of the following Javascript code?
<script>
document.getElementById("demo").innerHTML = typeof "John"
</script>
A. integer
B. number
C. string
D. error
Answer : C
37. Consider the following code snippet :
var c = counter(), d = counter();
c.count()
d.count()
c.reset()
c.count()
d.count()

The state stored in d is :
A. 1
B. 0
C. Null
D. Undefined
Answer : A
38. Consider the following code snippet :
var tensquared = (function(x) {return x*x;}(10));

Will the above code work ?
A. Yes, perfectly
B. Error
C. Exception will be thrown
D. Memory leak
Answer : A
39. JavaScript Code can be called by using ___________
A. RMI
B. Triggering Event
C. Preprocessor
D. Function/Method
Answer : D
40. What is the purpose of a return statement in a function?
A. Returns the value and continues executing rest of the statements, if any
B. Returns the value and stops the program
C. Returns the value and stops executing the function
D. Stops executing the function and returns the value
Answer : D
41. 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 : C
42. Consider the following code snippet.
for(var p in o)
console.log(o[p]);

The above code is equivalent to which code?
A. 
for (var i = 0;i < a.length;i++)
console.log(a[i]);

B. 
for (int i = 0;i < a.length;i++)
console.log(a[i]);

C. 
for (var i = 0;i <= a.length;i++)
console.log(a[i]);

D. 
for (var i = 1;i < a.length;i++)
console.log(a[i]);

Answer : A
43. What will be the step of the interpreter in a jump statement when an exception is thrown?
A. The interpreter stops its work
B. The interpreter throws another exception
C. The interpreter jumps to the nearest enclosing exception handler
D. The interpreter throws an error
Answer : C
44. What will be the output of the following JavaScript code?
int a=4;
int b=1;
int c=0;
If(a==b)
document.write(a);
else if(a==c)
document.write(a);
else
document.write(c);
A. 4
B. 1
C. Error
D. 0
Answer : D
45. What will be the output of the following Javascript code?
int a=0;
for(a;a<5;a++);
console.log(a);
A. 0
B. error
C. 4
D. 5
Answer : D
46. What will be the output of the following JavaScript code?
function output(object)
{
var place=object ? object.place : Italy;
return clean:+ place;
}
console.log(output({place:India}));
A. clean:India
B. clean:Italy
C. error
D. undefined
Answer : A
47. What will happen if the body of a for/in loop deletes a property that has not yet been enumerated?
A. The property will be stored in a cache
B. The loop will not run
C. That property will not be enumerated
D. The property will be enumerated
Answer : C
48. 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
Answer : A
49. What will be the output of the following JavaScript code?
var obj=
{
length:20,
height:35,
}
if (breadth' in obj === false)
{
obj.breadth = 12;
}
console.log(obj.breadth);
A. 20
B. 12
C. undefined
D. error
Answer : B
50. 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 : C
Downlaod JavaScript MCQ PDF

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