Explore topic-wise MCQs in Javascript.

This section includes 157 Mcqs, each offering curated multiple-choice questions to sharpen your Javascript knowledge and support exam preparation. Choose a topic below to get started.

1.

If we have an object r and want to know if it is a Range object, we can write:

A. typeof Range
B. is Range
C. equals Range
D. instanceof Range
Answer» E.
Discussion
2.

Which of the following is not a JavaScript framework?

A. ico
B. rototype
C. oco
D. oJo
Answer» E.
Discussion
3.

How can you find a client’s browser name?

A. rowser.name
B. avigator.appName
C. lient.navName
D. one of the mentioned
Answer» C. lient.navName
Discussion
4.

How do you find the number with the highest value of x and y?

A. eil(x,y)
B. op(x,y)
C. ath.ceil(x,y)
D. ath.max(x,y)
Answer» E.
Discussion
5.

What is the purpose of the function eval?

A. xecutes the string as an integer
B. ets the value of the string
C. xecuting string as JavaScript
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
6.

What is the purpose of a JavaScript debugger?

A. orrection of errors
B. lacing script execution under control
C. orrection of errors & Placing script execution under control
D. one of the mentioned
Answer» C. orrection of errors & Placing script execution under control
Discussion
7.

How do we debug a script?

A. se of JavaScript Validator
B. se of JavaScript Debugger
C. se of JavaScript Validator & Debugger
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
8.

What is the purpose of the mimeTypes property of a plug-in entry?

A. ontains MIME properties
B. ontains MIME sizes
C. ontains MIME types
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
9.

Which of the following are the properties of a plug-in entry?

A. ame
B. ilename
C. imeTypes
D. ll of the mentioned
Answer» E.
Discussion
10.

Which object is the top of the hierarchy?

A. indow Object
B. ocument Object
C. orm Object
D. orm Control Elements
Answer» B. ocument Object
Discussion
11.

What is the purpose of the Legacy DOM ?

A. akes the scripting easier
B. llows access to few keys and elements
C. ll of the mentioned
D. one of the mentioned
Answer» C. ll of the mentioned
Discussion
12.

What is the purpose of the Attr object in the HTML DOM?

A. sed to focus on a particular part of the HTML page
B. TML Attribute
C. sed to arrange elements
D. one of the mentioned
Answer» C. sed to arrange elements
Discussion
13.

What does the NamedNodeMap object represent in the HTML DOM?

A. nordered collection of elements
B. nordered collection of attributes
C. nordered collection of nodes
D. ll of the mentioned
Answer» E.
Discussion
14.

A Blob URL can be created using which of the following function?

A. reateURL()
B. reateObjectURL()
C. esignURL()
D. RLCreation()
Answer» C. esignURL()
Discussion
15.

Which is the function that allows a worker to terminate itself?

A. lose()
B. xit()
C. erminate()
D. alt()
Answer» B. xit()
Discussion
16.

Which property is used to manage multiple event handlers?

A. nmessage
B. nerror
C. oth onmessage and onerror
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
17.

Why shouldn’t JavaScript functions not be too long?

A. ser friendliness
B. ie up event loops
C. rowser becomes unresponsive
D. ll of the mentioned
Answer» E.
Discussion
18.

What is the function of the closure compiler?

A. ownload faster
B. un faster
C. oth Download faster and Run faster
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
19.

In what way does the closure compiler help in checking the code?

A. arnings
B. uddenly aborts
C. ejects malicious inputs
D. ll of the mentioned
Answer» B. uddenly aborts
Discussion
20.

When does one use the method startOverlays()?

A. dit ad request
B. elete ad request
C. reate ad request
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
21.

When does one use the event ready?

A. efore loading
B. uring loading
C. fter loading
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
22.

What is the purpose of the event disconnectionEvent?

A. layer demands for disconnection
B. layer disconnects from the channel
C. here is no user interaction
D. one of the mentioned
Answer» C. here is no user interaction
Discussion
23.

Which API makes the user’s current location available to browser-based application?

A. ava API
B. DL API
C. bject API
D. eolocation API
Answer» E.
Discussion
24.

What is the purpose of XMLHttpRequest?

A. ultiple loading
B. oad content by loading new document
C. oad content without loading new document
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
25.

Which program code doesn’t need preprocessing before being run?

A. ext
B. cript
C. oth Text and Script
D. one of the mentioned
Answer» C. oth Text and Script
Discussion
26.

Which of the following is the method used to add an element to the desired location?

A. dd.element()
B. lement.add()
C. lement.appendChild()
D. one of the mentioned
Answer» D. one of the mentioned
Discussion
27.

What is the purpose of the function parameter filetype?

A. ile type to be expected
B. ile type previously got
C. ile type that should not be got
D. one of the mentioned
Answer» B. ile type previously got
Discussion
28.

What is the purpose of the RegExp method test()?

A. ests for a match in its float parameter
B. ests for a match in its string parameter
C. ests for a match in its integer parameter
D. one of the mentioned
Answer» C. ests for a match in its integer parameter
Discussion
29.

Which of the following is a way to retain an object in memory?

A. onsole Log
B. losures
C. estory objects
D. ll of the mentioned
Answer» B. losures
Discussion
30.

When does a cycle occur during memory leak?

A. o reference occurs
B. wo objects reference
C. ne object gets referenced
D. ne object gets referenced
Answer» C. ne object gets referenced
Discussion
31.

Which of the following attribute takes the source of the PHP file?

A. mg
B. rc
C. ource
D. one of the mentioned
Answer» C. ource
Discussion
32.

Which of the following is added to prefs.js when the console is automatically opened during JavaScript error?

A. ser_pref("javascript.console.open_on_error", true);
B. ser_pref("javascript.console.open_error ", true);
C. ser_pref("javascript.console.open_error ", false);
D. ser_pref(" javascript.console.open_on_error", false);
Answer» B. ser_pref("javascript.console.open_error ", true);
Discussion
33.

What is the code snippet to change the class and let the stylesheet specify the details?~!

A. timestamp.className = "highlight";
B. timestamp.className = "change";
C. timestamp.className = "specify";
D. timestamp.className = "move";
Answer» B. timestamp.className = "change";
Discussion
34.

Which of the following is not an object?~!

A. Element
B. Location
C. Position
D. Window
Answer» D. Window
Discussion
35.

In what way is the closure compiler efficient?%!

A. Increases the size of the JavaScript files
B. Reduces the size of the JavaScript files
C. Reduces the execution time
D. Reduces the speed
Answer» C. Reduces the execution time
Discussion
36.

What is the function of the closure compiler?%!

A. Download faster
B. Run faster
C. Both Download faster and Run faster
D. None of the mentioned
Answer» D. None of the mentioned
Discussion
37.

Which of the following is a global object for a new worker?%!

A. WorkerGlobalScope
B. Worker
C. WorkerScope
D. Window
Answer» B. Worker
Discussion
38.

Which is the function that allows a worker to terminate itself?%!

A. close()
B. exit()
C. terminate()
D. halt()
Answer» B. exit()
Discussion
39.

During the traversing of the stack when you create a locally scoped variable, where does it go after it goes to the location?%!

A. Window
B. Function
C. Document
D. None of the mentioned
Answer» E.
Discussion
40.

Which algorithm supports blobs?%!

A. Structured clone algorithm
B. Double buffer algorithm
C. Chen’s algorithm
D. Retrieval algorithm
Answer» B. Double buffer algorithm
Discussion
41.

A Blob URL can be created using which of the following function?%!

A. createURL()
B. createObjectURL()
C. designURL()
D. URLCreation()
Answer» C. designURL()
Discussion
42.

The style property belongs to while of the following object?%!

A. Element
B. Window
C. Location
D. None of the mentioned
Answer» B. Window
Discussion
43.

In which format does JavaScript support external JavaScript?%!

A. .js
B. .php
C. .js/php
D. .jss
Answer» B. .php
Discussion
44.

What kind of path can the PHP file be?%!

A. Absolute
B. Relative
C. Either Absolute or Relative
D. Both Absolute and Relative
Answer» D. Both Absolute and Relative
Discussion
45.

What is the next step after calling the startTimeLogging()?%!

A. Interpret the code
B. Compile the code
C. Run the code
D. None of the mentioned
Answer» D. None of the mentioned
Discussion
46.

What is the work of the form control elements in the HTML DOM?%!

A. User Interface elements
B. All the possible elements
C. Debugging elements
D. None of the mentioned
Answer» B. All the possible elements
Discussion
47.

*$_What is the work of the form control elements in the HTML DOM??

A. User Interface elements
B. All the possible elements
C. Debugging elements
D. None of the mentioned
Answer» B. All the possible elements
Discussion
48.

*/*_In what way is the closure compiler efficient??

A. Increases the size of the JavaScript files
B. Reduces the size of the JavaScript files
C. Reduces the execution time
D. Reduces the speed
Answer» C. Reduces the execution time
Discussion
49.

*/*_During the traversing of the stack when you create a locally scoped variable, where does it go after it goes to the location??

A. Window
B. Function
C. Document
D. None of the mentioned
Answer» E.
Discussion
50.

*/*_Which of the following is a global object for a new worker??

A. WorkerGlobalScope
B. Worker
C. WorkerScope
D. Window
Answer» B. Worker
Discussion