Java Script Interview Questions and Answers

Are Java and JavaScript the same?
NO! Java and JavaScript are two completely different languages in both concept and design! Java (developed by Sun Microsystems) is a powerful and much more complex programming language - in the same category as C and C++. JavaScript’s syntax is loosely based on Java
Post comment
Thanks for your comment.!
Write a comment(Click here) ...
What is JavaScript?
JavaScript is a scripting language, designed to add interactivity to HTML pages, JavaScript is usually embedded directly into HTML pages, and JavaScript is an interpreted language (means that scripts execute without preliminary compilation) JavaScript is a platform-independent, event-driven, interpreted client-side scripting and programming language developed by Netscape Communications Corp. and Sun Microsystems.
Define JavaScript Variables?

JavaScript is case-sensitive, variable names are case-sensitive. Creating variables in JavaScript is most often referred to as "declaring" variables. You declare JavaScript variables with the var keyword:
Var x;
Var fu='hi';
Var gf=3.45;

What is variable typing in java script?
It is perfectly legal to assign a number to a variable and then assign a string to the same variable as follows example i = 10; i = 'stringchar'; This is called variable typing
How do you create an object in JavaScript?
var person = new Object; or var person = {};
What's relationship between JavaScript and ECMA Script?

ECMA Script is yet another name for JavaScript (other names include Live Script). The current JavaScript that you see supported in browsers is ECMA Script revision 3. Java Script is a scripting language that has been widely accepted for client side web development. However it originated from ECMA standards. ECMA and live scripts are just other names of java script.

What Boolean operators does JavaScript support?
&&, || ,!

What looping structures are there in JavaScript?
For, while, do-while loops
What is the difference between undefined value and null value?
Undefined means a variable has been declared but has not yet been assigned a value. On the other hand, null is an assignment value. It can be assigned to a variable as a representation of no value. Also, undefined and null are two distinct types: undefined is a type itself (undefined) while null is an object. Unassigned variables are initialized by JavaScript with a default value of undefined. JavaScript never sets a value to null. That must be done programmatically.
What data types are supported in Java Script?
Number, String, Undefined, null, Boolean

Explain a JavaScript Comments?

Comments can be added to explain the JavaScript, or to make the code more readable.
Single line comments start with //.
Multi line comments start with /* and end with */

What does the tag do?
Displayed the text enclosed within tag when JavaScript is disabled
What is === operator in JavaScript and how it is different from == operator?

=== operator checks for the equality. It gives true when both the compared values are having same value and same data type as === does not perform any type conversion while comparing. 

It is different from == as == does the type conversion while comparing.

What is the difference between JavaScript and Jscript?

Jscript supports more rich set of functionality/commands than the java script, through which ActiveX and local computer can be accessed. These commands are used in an intranet where the connecting computer's configuration is known and they are all being accessed using Internet Explorer. While java script targets unknown machine configuration and Jscript cannot for which java script are suitable for internet which Jscripts are not.

What is the main difference between Client side JavaScript and Server side Java Script? How actually they run on both side?

To state the main difference, JavaScript at the client side does not require a web server to make it run instead it uses the client's processor for this purpose. This eradicates the portability issue. But in server side JavaScript deployment, portability, configuration are major and vast issues and requires a web server to run the script within a page before rendering its output as a response html page.

How can JavaScript make a Web site easier to use?
JavaScript’s run on the client side which saves the server roundtrip time for small processing. It means that it makes web pages more interactive as everything is not required to be submitted at the server. Let’s consider a small clock if controlled by the server then the transmission time will make the clock faulty in this case java script is used.
How do we get JavaScript onto a web page?

The script element can directly be added inside the body of the page. It should start with the tag <script> and end with </script> tag. The script can also be added to the head tag of the web page. Similarly the other way is by placing the script in a separate file which gets downloaded on the client's machine when the page is requested.
<SCRIPT LANGUAGE='JavaScript Version'> JavaScript statements </SCRIPT>
Stored externally
<SCRIPT src='abc.js' />

Latest Updates


Choose appropriate article for the given sentence:
__________ teachers had ________ late lunch as their meeting lasted longer than___ hour.

Child Development & Pedagogy

Which of the following is the most effective way to create interest for learning in a student?

The rules of presenting the content to make them easy are called_________?

The term SLD in children’s mental health denotes for?

The child will be able to use proper sentences by the age of?

Indian Politics

______is an institutional mechanism to provide representation to the states of India?

Books and Authors

Which text is not written by Kalidasa?

Indian Constitution

Which Constitutional Amendment introduced Right to Education as a Fundamental Right?

Indian History

Which animal is engraved on Harappan seals?

Indian Politics

Who is known for initiating electoral reforms in India to ensure free and fair elections?

Indian Constitution

The sequence in which the given terms are mentioned in the preamble to the Constitution of India is?

Which of the following parts of the Constitution of India provides fundamental rights ?

Books and Authors

Who among the following is the author of ‘Politics’?

Which one is the text not written by Abul Fazl?

Which King was the author of Ratnawali, Nagananda, Priyadarsika?

Fill in the blank

Fill in the blanks with the most appropriate preposition in the given sentence.
The class begins _______ 7:30 am _____ the morning.

The workers were so skilled that their _____ was quite visible even to a layman.


Choose appropriate article for the given sentence:
______ German is ___ easy language to learn for English speaking students.

Latest Job Notifications

Banking Jobs

बैंकिंग कार्मिक चयन संस्थान Institute of Banking Personnel Selection(IBPS) - 7855 पद - 29/07/2022 अंतिम तिथि

SSC Recruitment

कर्मचारी चयन आयोग (एसएससी) Staff Selection Commission (SSC) - 1411 पद - 29/07/2022 अंतिम तिथि

Jobs in Rajasthan

राजस्थान अधीनस्थ और मंत्रिस्तरीय सेवा चयन बोर्ड Rajasthan Subordinate and Ministerial Services Selection Board (RSMSSB) - 5546 पद - 22-Jul-2022 अंतिम तिथि

Railway Recruitment

उत्तर मध्य रेलवे भर्ती प्रकोष्ठ Railway Recruitment Cell(NCR) - 1659 पद - 01/08/2022 अंतिम तिथि

Jobs in West Bengal

इंडियन पोस्ट सर्विस Indian Post Service - 2357 पद - 19/08/2021 अंतिम तिथि - पश्चिम बंगाल पोस्टल सर्कल

Banking Jobs

भारतीय स्टेट बैंक State Bank of India(SBI) - 6100 पद - 26/07/2021 अंतिम तिथि - CRPD/APPR/2021-22/10

SSC Recruitment

कर्मचारी चयन आयोग Staff Selection Commission(SSC) - 25271 पद - 31/08/2021 अंतिम तिथि

Jobs in Madhya Pradesh

राष्ट्रीय स्वास्थ्य मिशन मध्य प्रदेश National Health Mission MP(NRHM) - 5215 पद - 22/06/2021 अंतिम तिथि

Jobs in Punjab

पंजाब स्टेट पावर कॉर्पोरेशन लिमिटेड Punjab State Power Corporation Limited (PSPCL) - 2632 पद - 20/06/2021 अंतिम तिथि

Jobs in Chhattisgarh

स्वास्थ्य सेवा निदेशालय, छत्तीसगढ़ Department of Health & Family Welfare, Chhattisgarh - 267 पद - 26/06/2021 अंतिम तिथि