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JavaScript 1000+ MCQ with answer for SBI PO

Thursday 9th of March 2023

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1. 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
2. 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
3. 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
4. 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
5. 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
6. 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
7. A function definition expression can be called as __________
A. Function prototype
B. Function literal
C. Function calling
D. Function declaration
Answer : B
8. 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
9. 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
10. 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
11. 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
12. 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
13. 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
14. 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
15. 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
16. What will be the output of the following JavaScript code?
function compare()
{
int a=1;
char b=1;
if(a.tostring()===b)
return true;
else
return false;
}
A.true
B. false
C. runtime error
D. logical error
Answer : A
17. 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
18. 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
19. JavaScript is a _______________ language.
A. Object-Oriented
B. High-level
C. Assembly-language
D. Object-Based
Answer : D
20. 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
21. 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
22. Among the keywords below, which one is not a statement?
A. debugger
B. with
C. if
D. use strict
Answer : D
23. Among the following, which one is a ternary operator?
A. +
B. :
C. ^
D. ?:
Answer : D
24. 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
25. 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
26. 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
27. 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
28. 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
29. 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
30. The purpose of extensible attribute is to __________
A. make all of the own properties of that object non configurable
B. to configure and bring a writable property
C. lock down objects into a known state and prevent outside tampering
D. to include new properties into the object
Answer : C
31. 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
32. JavaScript is ideal to ________
A. make computations in HTML simpler
B. minimize storage requirements on the web server
C. increase the download time for the client
D. increase the loading time of the website
Answer : B
33. Consider the following JavaScript statements.
var text = testing: 1, 2, 3; // Sample text
var pattern = /d+/g // Matches all instances of one or more digits

In order to check if the pattern matches with the string text, the statement is ____________
A. text==pattern
B. text.equals(patern)
C. text.test(pattern)
D. pattern.test(text)
Answer : D
34. 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
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. JavaScript Code can be called by using ___________
A. RMI
B. Triggering Event
C. Preprocessor
D. Function/Method
Answer : D
37. 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
38. 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
39. What will be the output of the following Javascript code?
<script>
txt1 = “ one”;
txt1 += “two”;
document.getElementById("demo").innerHTML = txt1;
</script>
A. onetwo
B. one two
C. error
D. undefined
Answer : A
40. 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
41. Which keyword is used to define the function in javascript?
A. void
B. int
C. function
D. main
Answer : C
42. 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
43. 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
44. 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
45. 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
46. 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
47. 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
48. 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
49. 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
50. 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
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