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CLAT PG - JavaScript 1000+ MCQ [Solved] PDF Download

Thursday 9th of March 2023

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Downlaod JavaScript MCQ PDF
1. What will be the output of the following Javascript code?
function range(int length)
{
int a=5;
for(int i=0;i<length;i++)
{
console.log(a);
}
}
range(3);
A. 5
B. 555
C. 3
D. error
Answer : B
2. The script tag must be placed in __________
A. the head tag
B. the head or body
C. the title or head
D. after the body tag
Answer : B
3. 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
Answer : B
4. 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
5. One of the special feature of an interpreter in reference with the for loop is that ___________
A. Before each iteration, the interpreter evaluates the variable expression and assigns the name of the property
B. The iterations can be infinite when an interpreter is used
C. The body of the loop is executed only once
D. the iteration is finite when an interpreter is used
Answer : A
6. The escape sequence stands for _________
A. Floating numbers
B. Representation of functions that returns a value
C. is not present in JavaScript
D. Form feed
Answer : D
7. The type of a variable that is volatile is _______________
A. Volatile variable
B. Mutable variable
C. Immutable variable
D. Dynamic variable
Answer : B
8. 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
9. 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
10. 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 : D
11. 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
12. 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
Answer : B
13. JavaScript Code can be called by using ____________
A. RMI
B. Triggering Event
C. Preprocessor
D. Function/Method
Answer : D
14. 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
15. The var and function are __________
A. Keywords
B. Declaration statements
C. Data types
D. Prototypes
Answer : B
16. 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
17. What will be the step of the interpreter ina 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
18. A linkage of series of prototype objects is called as ________
A. prototype stack
B. prototype chain
C. prototype class
D. prototypes
Answer : B
19. Consider the following code snippet
function f(o)
{
if (o === undefined) debugger;
}

What could be the task of the statement debugger?
A. It does nothing but a simple breakpoint
B. It debugs the error in that statement and restarts the statements execution
C. It is used as a keyword that debugs the entire program at once
D. It is used to find error in the statement
Answer : A
20. What will be the output of the following JavaScript code?
var grade='A';
var result;
switch(grade)
{
case 'A':
result+=10;
case 'B':
result+= 9;
case 'C':
result+= 8;
default:
result+= 0;
}
document.write(result);
A. 10
B. 27
C. 8
D. 0
Answer : B
21. 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
22. 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
23. 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
24. A proper scripting language is a __________
A. High level programming language
B. Assembly level programming language
C. Machine level programming language
D. Low level programming language
Answer : A
25. 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
26. What are the three important manipulations done in a for loop on a loop variable?
A. Updation, Incrementation, Initialization
B. Initialization,Testing, Updation
C. Testing, Updation, Testing
D. Initialization,Testing, Incrementation
Answer : B
27. The reduce and reduceRight methods follow a common operation called __________
A. filter and fold
B. inject and fold
C. finger and fold
D. fold
Answer : B
28. In the following switch syntax, the expression is compared with the case labels using which of the following operator(s)?
switch(expression)
{
statements
}
A. ==
B. equals
C. equal
D. ===
Answer : D
29. 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
30. When an empty statement is encountered, a JavaScript interpreter __________
A. Ignores the statement
B. Prompts to complete the statement
C. Throws an error
D. Shows a warning
Answer : A
31. What will be the output of the following Javascript code?
var a = 10;
do {
a += 1;
console.log(a);
} while (a < 5);
A. 11121314
B. 1112
C. 12345
D. 11
Answer : D
32. Which attribute is used to specify that the script is executed when the page has finished parsing? (only for external scripts)
A. parse
B. a sync
C. defer
D. type
Answer : C
33. The var and function are __________
A. Keywords
B. Declaration statements
C. Data types
D. Prototypes
Answer : B
34. 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
35. A JavaScript program developed on a Unix Machine ________
A. will throw errors and exceptions
B. must be restricted to a Unix Machine only
C. will work perfectly well on a Windows Machine
D. will be displayed as a JavaScript text on the browser
Answer : C
36. What will be the output of the following JavaScript code?
int a=1;
if(a!=null)
return 1;
else
return 0;
A. 1
B. 0
C. runtime error
D. compiler error
Answer : A
37. Consider the following code snippet :
var string2Num=parseInt(123xyz);

The result for the above code snippet would be :
A. 123
B. 123xyz
C. Exception
D. NaN
Answer : A
38. 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
39. What will be the output of the following JavaScript code?
var grade='A';
var result;
switch(grade)
{
case 'A':
result+=10;
case 'B':
result+= 9;
case 'C':
result+= 8;
default:
result+= 0;
}
document.write(result);
A. 10
B. 27
C. 8
D. 0
Answer : B
40. What will be the output of the following JavaScript code?
function code(id,name)
{
this.id = id;
this.name = name;
}
function pcode(id,name)
{
code.call(this,id,name);
}
document.writeln(new pcode(101,vivek).id);
A. vivek
B. 101
C. Runtime error
D. Compilation error
Answer : B
41. 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
42. 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
43. 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);
Answer : D
44. The web development environment (JavaScript) offers which standard construct for data validation of the input entered by the user.
A. Controlled loop constructs
B. Case checking constructs
C. Validation constructs
D. All of the mentioned
Answer : D
45. Assume that we have to convert false that is a non-string to string. The command that we use is (without invoking the new operator).
A. false.toString()
B. String(false)
C. String newvariable=false
D. Both false.toString() and String(false)
Answer : D
46. 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
47. What will be the output of the following JavaScript code?
var string1 = 123;
var intvalue = 123;
alert( string1 + intvalue );
A. 123246
B. 246
C. 123123
D. Exception
Answer : C
48. Among the keywords below, which one is not a statement?
A. debugger
B. with
C. if
D. use strict
Answer : D
49. 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
50. A hexadecimal literal begins with __________
A. 00
B. 0x
C. 0X
D. Both 0x and 0X
Answer : D
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