JavaScript - Interview Questions and Answers

31) Difference between Client side JavaScript and Server side JavaScript?

Client-side JavaScript comprises the basic language and predefined objects which are relevant to running JavaScript in a browser. The client-side JavaScript is embedded directly by in the HTML pages. The browser interprets this script at runtime.

Server-side JavaScript also resembles client-side JavaScript. It has a relevant JavaScript which is to run in a server. The server-side JavaScript are deployed only after compilation.

32) In which location cookies are stored on the hard disk?

The storage of cookies on the hard disk depends on the OS and the browser.

The Netscape Navigator on Windows uses a cookies.txt file that contains all the cookies. The path is c:\Program Files\Netscape\Users\username\cookies.txt

The Internet Explorer stores the cookies on a file username@website.txt. The path is: c:\Windows\Cookies\username@Website.txt.

33) What is the real name of JavaScript?

The original name was Mocha, a name chosen by Marc Andreessen, founder of Netscape. In September of 1995, the name was changed to LiveScript. In December 1995, after receiving a trademark license from Sun, the name JavaScript was adopted.

34) What is the difference between undefined value and null value?

Undefined value: A value that is not defined and has no keyword is known as undefined value. For example:

Null value: A value that is explicitly specified by the keyword "null" is known as a null value. For example:

35) How to set the cursor to wait in JavaScript?

The cursor can be set to wait in JavaScript by using the property "cursor". The following example illustrates the usage:

36) What is this [[[]]]?

This is a three-dimensional array.

37) Are Java and JavaScript same?

No, Java and JavaScript are the two different languages. Java is a robust, secured and object-oriented programming language whereas JavaScript is a client-side scripting language with some limitations.

38) What is negative infinity?

Negative Infinity is a number in JavaScript which can be derived by dividing the negative number by zero. For example:

 var num=-5; function display() {   document.writeln(num/0); } display(); //expected output: -Infinity 

39) What is the difference between View state and Session state?

"View state" is specific to a page in a session whereas "Session state" is specific to a user or browser that can be accessed across all pages in the web application.

40) What are the pop-up boxes available in JavaScript?

Alert Box
Confirm Box
Prompt Box

Example of alert() in JavaScript

 <script type="text/javascript"> function msg(){  alert("Hello Alert Box"); } </script> <input type="button" value="click" onclick="msg()"/> 

Example of confirm() in JavaScript

 <script type="text/javascript"> function msg(){ var v= confirm("Are u sure?"); if(v==true){ alert("ok"); } else{ alert("cancel"); }  } </script>  <input type="button" value="delete record" onclick="msg()"/>  

Example of prompt() in JavaScript

 <script type="text/javascript"> function msg(){ var v= prompt("Who are you?"); alert("I am "+v);  } </script>  <input type="button" value="click" onclick="msg()"/>  

Interview :: JavaScript

Example of alert() in JavaScript

Example of confirm() in JavaScript

Example of prompt() in JavaScript