Explore topic-wise MCQs in Javascript.

This section includes 302 Mcqs, each offering curated multiple-choice questions to sharpen your Javascript knowledge and support exam preparation. Choose a topic below to get started.

1.

Consider the following code snippetfunction tail(o){for (; o.next; o = o.next) ;return o;}Will the above code snippet work? If not, what will be the error?

A. o, this will throw an exception as only numerics can be used in a for loop
B. o, this will not iterate
C. es, this will work
D. o, this will result in a runtime error with the message “Cannot use Linked List”
Answer» D. o, this will result in a runtime error with the message “Cannot use Linked List”
2.

Consider the following code snippetfunction 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. rints the numbers in the array in order
B. rints the numbers in the array in the reverse order
C. rints 0 to the length of the array
D. rints “Empty Array”
Answer» B. rints the numbers in the array in the reverse order
3.

Consider the following statementsvar count = 0;while (count < 10){.log(count);count++;}In the above code snippet, what happens?

A. he values of count is logged or stored in a particular location or storage
B. he value of count from 0 to 9 is displayed in the console
C. n error is displayed
D. n exception is thrown
Answer» C. n error is displayed
4.

“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. roperties
B. rototypes
C. value
D. efinition
Answer» D. efinition
5.

Which is a more efficient code snippet ?Code 1 :for(var=10;num>=1;num--){document.writeln(num);}Code 2 :var num=10;while(num>=1){document.writeln(num);num++;}

A. ode 1
B. ode 2
C. oth Code 1 and Code 2
D. annot Compare
Answer» B. ode 2
6.

Consider the following statementsvar text = "testing: 1, 2, 3"; // Sample textvar pattern = /d+/g // Matches all instances of one or more digitsIn order to check if the pattern matches with the string “text”, the statement is

A. ext==pattern
B. ext.equals(pattern)
C. ext.test(pattern)
D. attern.test(text)
Answer» E.
7.

Consider the following snippet codevar string1 = ”123”;var intvalue = 123;alert( string1 + intvalue )The result would be

A. 23246
B. 46
C. 23123
D. xception
Answer» D. xception
8.

Identify the process done in the below code snippeto = {x:1, y:{z:[false,null,"]}};s = JSON.(o);p = JSON.parse(s);

A. bject Encapsulation
B. bject Serialization
C. bject Abstraction
D. bject Encoding
Answer» C. bject Abstraction
9.

Consider the below given syntaxbook[datatype]=assignment_value;In the above syntax, the datatype within the square brackets must be

A. n integer
B. String
C. n object
D. one of the mentioned
Answer» C. n object
10.

Consider the following code snippet :var book = {"main title": "JavaScript",'sub-title': "The Definitive Guide","for": "all audiences",author: {firstname: "David",surname: "Flanagan"}};In the above snippet, firstname and surname are

A. roperties
B. roperty values
C. roperty names
D. bjects
Answer» D. bjects
11.

Consider the following code snippetfunction f(o){if (o === undefined) debugger;}What could be the task of the statement debugger?

A. t does nothing but a simple breakpoint
B. t debugs the error in that statement and restarts the statement’s execution
C. t is used as a keyword that debugs the entire program at once
D. ll of the mentioned
Answer» B. t debugs the error in that statement and restarts the statement’s execution
12.

Consider the following code snippetwhile (a != 0){if (spam>a == 1)continue;else++;}What will be the role of the continue keyword in the above code snippet?

A. he continue keyword restarts the loop
B. he continue keyword skips the next iteration
C. he continue keyword skips the rest of the statements in that iteration
D. one of the mentioned
Answer» D. one of the mentioned
13.

Among the following, which one is a ternary operator?

A. +
B. :
C.
D. ?:
Answer» E.
14.

What kind of an expression is “new Point(2,3)”?

A. Primary Expression
B. Object Creation Expression
C. Invocation Expression
D. Constructor Calling Expression
Answer» C. Invocation Expression
15.

JavaScript is a _______________ language

A. Object-Oriented
B. High-level
C. Assembly-language
D. Object-Based
Answer» E.
16.

A conditional expression is also called a

A. Alternate to if-else
B. Immediate if
C. If-then-else statement
D. None of the mentioned
Answer» C. If-then-else statement
17.

A statement block is a

A. conditional block
B. block that contains a single statement
C. Both conditional block and single statement
D. block that combines multiple statements into a single compound statement
Answer» E.
18.

The “var” and “function” are

A. Keywords
B. Declaration statements
C. Datatypes
D. Prototypes
Answer» C. Datatypes
19.

Consider the following statements switch(expression) { statements } In the above switch syntax, the expression is compared with the case labels using which of the following operator(s) ?

A.
B. equals
C. equal
D.
Answer» E.
20.

Consider the following statements var count = 0; while (count < 10) { console.log(count); count++; } In the above code snippet, what happens?

A. The values of count is 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» C. An error is displayed
21.

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» B. The object does not have the properties present in the integer array indices
22.

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» B. Prints the numbers in the array in the reverse order
23.

Consider the following code snippet function tail(o){ for (; o.next; o = o.next) ; return o; }Will the above code snippet work? If not, what will be the error?

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» D. No, this will result in a runtime error with the message “Cannot use Linked List”
24.

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. All of the mentioned
Answer» B. The iterations can be infinite when an interpreter is used
25.

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. All of the mentioned
Answer» D. All of the mentioned
26.

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. None of the mentioned
Answer» D. None of the mentioned
27.

Local Browser used for validations on the Web Pages uses __________.

A. Java
B. HTML
C. CSS
D. JS
Answer» E.
28.

JavaScript is also called as _____________.

A. Server Side Scripting Language
B. Browser Side Scripting Language
C. Client Side Scripting Language
D. Both B and C
Answer» E.
29.

Why JavaScript is called as Lightweight Programming Language ?

A. because JS is available free of cost
B. because JS is client side scripting
C. because we can add programming functionality inside JS
D. because JS can provide programming functionality inside but up to certain extend.
Answer» E.
30.

JavaScript Code is written inside file having extension __________.

A. .jvs
B. .javascript
C. .js
D. .jsc
Answer» D. .jsc
31.

Cost for Using JavaScript in your HTML is _________ .

A. Its Free !!!
B. $10 / Year
C. $15 / Year
D. $5 / Year
Answer» B. $10 / Year
32.

JavaScript is designed for following purpose -

A. To Style HTML Pages
B. To add interactivity to HTML Pages.
C. To Perform Server Side Scripting Opertion
D. To Execute Query Related to DB on Server
Answer» C. To Perform Server Side Scripting Opertion
33.

Javascript is _________ language.

A. Programming
B. Application
C. None of These
D. Scripting
Answer» E.
34.

What would be the output of the following fraction of code ? int Integer = 34 ; char String = 'S' ; System.out.print( Integer ) ; System.out.print( String ) ;

A. Does not compile as Integer and String are API class names.
B. 34
C. S
D. 34 S
Answer» E.
35.

What will be output of the following program code? public class Test{ public static void main(String[] a) { short x = 10; x = x*5; System.out.print(x); } }

A. 50
B. 10
C. Compilation Error
D. None of these
Answer» D. None of these
36.

The following fraction of code double STATIC = 2.5 ; System.out.println( STATIC );

A. Prints 2.5
B. Rraises an error as STATIC is used as a variable which is a keyword
C. Raises an exception
D. None of these
Answer» B. Rraises an error as STATIC is used as a variable which is a keyword
37.

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» B. Assembly level programming language
38.

Which environment variable must the user enable in order to enable data tainting?

A. ENABLE_TAINT
B. MS_ENABLE_TAINT
C. NS_ENABLE_TAINT
D. ENABLE_TAINT_NS
Answer» D. ENABLE_TAINT_NS
39.

Which tag can handle mouse events in Netscape?

A. img
B. a
C. br
D. none of the mentioned
Answer» B. a
40.

What will the file_get_contents() return?

A. Server’s response
B. Errors
C. Exception
D. Client’s response
Answer» B. Errors
41.

What is the purpose of the file_get_contents()?

A. To get the errors and exceptions
B. To get the client’s response
C. To get the server’s response
D. None of the mentioned
Answer» D. None of the mentioned
42.

What is the purpose of getting the paramerer fvonly?

A. To repeat the view test
B. To get the first view
C. To debug the code
D. None of the mentioned
Answer» C. To debug the code
43.

What will happen if you set the private flag as 1?

A. Test will be run only by the administrator
B. Test will not be run
C. Test is public
D. Test is not displayed in public
Answer» E.
44.

What is the purpose of the method par()?

A. Makes the text vertical
B. Makes the text horizontal
C. Makes the text diagonal
D. None of the mentioned
Answer» C. Makes the text diagonal
45.

What is the purpose of the method symbols in R?

A. Draw symbols
B. Draw other shapes
C. Draw symbols and other shapes
D. None of the mentioned
Answer» C. Draw symbols and other shapes
46.

What is the purpose of the method plot()?

A. Displays symbols
B. Displays charts
C. Displays symbols and charts
D. None of the mentioned
Answer» C. Displays symbols and charts
47.

Which function is used to create data frames?

A. data.frames()
B. frame.data()
C. data.frame()
D. frame(data)
Answer» D. frame(data)
48.

Which of the following list contains multiple data types?

A. Vectors
B. Data frames
C. Matrices
D. None of the mentioned
Answer» C. Matrices
49.

Which is the function used to add the vectors?

A. c()
B. add(vectors)
C. c(vectors)
D. vectors.add
Answer» B. add(vectors)
50.

Which of the following is the assignment operator?

A. <-
B. ->
C. =
D.
Answer» B. ->