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1000+ JavaScript Multiple Choice Question Answer [Solved]

Thursday 9th of March 2023

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1. The method or operator used to identify the array is __________
A. isarrayType()
B. ==
C. ===
D. typeof
Answer : D
2. 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
3. What is the observation made in the following JavaScript code?
var count = [1,,3];
A. The omitted value takes undefined
B. This results in an error
C. This results in an exception
D. The omitted value takes an integer value
Answer : A
4. Consider the following code snippet :
function constfuncs()
{
var funcs = [];
for(var i = 0; i < 10; i++)
funcs[i] = function() { return i; };
return funcs;
}
var funcs = constfuncs();
funcs[5]()

What does the last statement return ?
A. 9
B. 0
C. 10
D. None of the mentioned
Answer : C
5. 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
6. An expression that can legally appear on the left side of an assignment expression. is a well known explanation for variables, properties of objects, and elements of arrays. They are called ___________
A. Properties
B. Prototypes
C. Lvalue
D. Definition
Answer : C
7. 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
8. 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
9. 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
10. Consider the following code snippet.
while (a != 0)
{
if (a == 1)
continue;
else
a++;
}

What will be the role of the continue keyword in the above code snippet?
A. The continue keyword restarts the loop
B. The continue keyword skips the next iteration
C. The continue keyword skips the rest of the statements in that iteration
D. The continue keyword breaks out of the loop
Answer : C
11. JavaScript is a _______________ language.
A. Object-Oriented
B. High-level
C. Assembly-language
D. Object-Based
Answer : D
12. What will be the output of the following Javascript code?
var txt1 = good;
var txt2 = day;
document.getElementById(demo).innerHTML = txt1 + txt2;

 
A. good day
B. goodday
C. error
D. undefined
Answer : B
13. 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
14. 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
15. 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
16. 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
17. 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
18. Which keyword is used to define the function in javascript?
A. void
B. int
C. function
D. main
Answer : C
19. What will happen if reverse() and join() methods are used simultaneously?
A. Reverses and stores in the same array
B. Reverses and concatenates the elements of the array
C. Reverses
D. Stores the elements of an array in normal order
Answer : A
20. 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
21. 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
22. Consider the following code snippet.
while (a != 0)
{
if (a == 1)
continue;
else
a++;
}

What will be the role of the continue keyword in the above code snippet?
A. The continue keyword restarts the loop
B. The continue keyword skips the next iteration
C. The continue keyword skips the rest of the statements in that iteration
D. The continue keyword breaks out of the loop
Answer : C
23. 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
24. 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
25. What will be the output of the following JavaScript code?
function info()
{
int a=1;
int b=2;
return a*b;
}
document.write(info());
A. 1
B. 2
C. 3
D. error
Answer : B
26. The var and function are __________
A. Keywords
B. Declaration statements
C. Data types
D. Prototypes
Answer : B
27. A hexadecimal literal begins with __________
A. 00
B. 0x
C. 0X
D. Both 0x and 0X
Answer : D
28. 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
29. 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
30. What happens in the following javaScript code snippet?
var count = 0;
while (count < 10)
{
console.log(count);
count++;
}
A. The values of count are logged or stored in a particular location or storage
B. The value of count from 0 to 9 is displayed in the console
C. An error is displayed
D. An exception is thrown
Answer : B
31. The generalised syntax for a real number representation is __________
A. [digits][.digits][(E|e)[(+|-)]digits]
B. [digits][+digits][(E|e)[(+|-)]digits]
C. [digits][(E|e)[(+|-)]digits]
D. [.digits][digits][(E|e)[(+|-)]digits]
Answer : A
32. 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 : B
33. 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;br>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
34. 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
35. What will be the output of the following JavaScript code?
var grade='E';
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. 0
C. 18
D. 17
Answer : B
36. What will be the output of the following JavaScript code?
function output(option)
{
return (option ? yes : no);
}
bool ans=true;
console.log(output(ans));
A. Yes
B. No
C. Runtime error
D. Compilation error
Answer : A
37. What will be the output of the following JavaScript code?
A. 7.25
B. -7.25
C. 7
D. -7
Answer : A
38. 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
39. 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
40. 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
41. 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
42. For the below mentioned code snippet:
var o = new Object();

The equivalent statement is:
A. var o = Object();
B. var o;
C. var o= new Object;
D. Object o=new Object();
Answer : C
43. 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
44. Consider the following code snippet.
function printArray(a)
{
var len = a.length, i = 0;
if (len == 0)
console.log(Empty Array);
else
{
do
{
console.log(a[i]);
} while (++i < len);
}
}

What does the above code result?
A. Prints the numbers in the array in order
B. Prints the numbers in the array in the reverse order
C. Prints 0 to the length of the array
D. Prints Empty Array
Answer : A
45. What happens in the following javaScript code snippet?
var count = 0;
while (count < 10)
{
console.log(count);
count++;
}
A. The values of count are logged or stored in a particular location or storage
B. The value of count from 0 to 9 is displayed in the console
C. An error is displayed
D. An exception is thrown
Answer : B
46. What will be the output of the following JavaScript code?
function printprops(o)
{
for(var p in o)
console.log(p + : + o[p] +
);
}
A. Prints the contents of each property of o
B. Returns undefined
C. Prints only one property
D. Prints the address of elements
Answer : B
47. What will be the output of the following JavaScript code?
var pow=new Function(num1,num2,return Math.pow(num1,num2));
document.writeln(pow(2,3));
A. 2
B. 3
C. 8
D. error
Answer : C
48. What will be the output of the following Javascript code?
var a= 0;
var b = 0;
while (a < 3)
{
a++;
b += a;
console.log(b);
}
A. 135
B. 123
C. 013
D. 01
Answer : A
49. JavaScript Code can be called by using ___________
A. RMI
B. Triggering Event
C. Preprocessor
D. Function/Method
Answer : D
50. 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
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