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1000+ JavaScript Multiple Choice Question Answer [Solved]

Thursday 9th of March 2023

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1. What is the prototype represents in the following JavaScript code snippet?
function f() {};
A. Function f
B. A custom constructor
C. Prototype of a function
D. Not valid
Answer : B
2. The unordered collection of properties, each of which has a name and a value is called _________
A. String
B. Object
C. Serialized Object
D. Array
Answer : B
3. 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
4. A function with no return value is called ___________
A. Procedures
B. Method
C. Static function
D. Dynamic function
Answer : A
5. 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
6. What will be the output of the following JavaScript code?
var person =
{
name: Rahul,
getName: function()
{
nreturn this.name;
}
}
var unboundName = person.getName;
var boundName = unboundName.bind(person);
document.writeln(boundName());
A. runtime error;
B. compilation error
C. Rahul
D. undefined
Answer : C
7. 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
8. 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
9. 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
10. What will be the output of the following JavaScript code?
A. 7.25
B. -7.25
C. 7
D. -7
Answer : A
11. 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
12. 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
13. 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
14. 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
15. 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
16. 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
17. 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 statments into a single compound statement
Answer : D
18. 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
19. 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
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. Which keyword is used to define the function in javascript?
A. void
B. int
C. function
D. main
Answer : C
22. 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
23. The basic purpose of the toLocaleString() is to _________
A. return a localised object representation
B. return a parsed string
C. return a local time in the string format
D. return a localized string representation of the object
Answer : D
24. JavaScript Code can be called by using ____________
A. RMI
B. Triggering Event
C. Preprocessor
D. Function/Method
Answer : D
25. 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
26. 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
27. 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 : D
28. 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
29. 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
30. 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
31. 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
32. 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
33. What will be the output of the following JavaScript code?
A. 125
B. 25
C. 5
D. Error
Answer : C
34. What will be the output of the following Javascript code?
int size=5;
int a=5;
int size=4;
for(int j=size;j>=0;j--)
{
console.log(a);
a=a-2;
}
A. 5555
B. 5321
C. 531-1
D. 531
Answer : C
35. 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
36. 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
37. 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
38. What kind of expression is new Point(2,3)?
A. Primary Expression
B. Object Creation Expression
C. Invocation Expression
D. Constructor Calling Expression
Answer : B
39. 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
40. A conditional expression is also called a _______________
A. Alternative to if-else
B. Immediate if
C. If-then-else statement
D. Switch statement
Answer : B
41. What will be the output of the following JavaScript code?
var arr = [7, 5, 9, 1];
var value = Math.max.apply(null, arr);
document.writeln(value);
A. 7
B. 5
C. 1
D. 9
Answer : D
42. 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
43. Among the keywords below, which one is not a statement?
A. debugger
B. with
C. if
D. use strict
Answer : D
44. What will be the possible output of the following JavaScript code?
var a = [1,2,3,4,5];
a.slice(0,3);
A. Returns [1,2,3]
B. Returns [4,5]
C. Returns [1,2,3,4]
D. Returns [1,2,3,4,5]
Answer : C
45. 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
46. 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
47. Among the following, which one is a ternary operator?
A. +
B. :
C. ^
D. ?:
Answer : D
48. A hexadecimal literal begins with __________
A. 00
B. 0x
C. 0X
D. Both 0x and 0X
Answer : D
49. 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
50. 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
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