Sunday, June 22, 2008

50 JavaScript Interview Questions

D,A,B,C,C,A, B,B,A,B,B,D,A,A,C,D
1. Why so JavaScript and Java have similar name?

A. JavaScript is a stripped-down version of Java

B. JavaScript's syntax is loosely based on Java's

C. They both originated on the island of Java

D. None of the above

2. When a user views a page containing a JavaScript program, which machine actually executes the script?

A. The User's machine running a Web browser

B. The Web server

C. A central machine deep within Netscape's corporate offices

D. None of the above

3. ______ JavaScript is also called client-side JavaScript.

A. Microsoft

B. Navigator

C. LiveWire

D. Native

4. __________ JavaScript is also called server-side JavaScript.

A. Microsoft

B. Navigator

C. LiveWire

D. Native

5. What are variables used for in JavaScript Programs?

A. Storing numbers, dates, or other values

B. Varying randomly

C. Causing high-school algebra flashbacks

D. None of the above

6. _____ JavaScript statements embedded in an HTML page can respond to user events such as mouse-clicks, form input, and page navigation.

A. Client-side

B. Server-side

C. Local

D. Native

7. What should appear at the very end of your JavaScript?

The <script LANGUAGE="JavaScript">tag

A. The </script>

B. The <script>

C. The END statement

D. None of the above

8. Which of the following can't be done with client-side JavaScript?

A. Validating a form

B. Sending a form's contents by email

C. Storing the form's contents to a database file on the server

D. None of the above

9. Which of the following are capabilities of functions in JavaScript?

A. Return a value

B. Accept parameters and Return a value

C. Accept parameters

D. None of the above

10. Which of the following is not a valid JavaScript variable name?

A. 2names

B. _first_and_last_names

C. FirstAndLast

D. None of the above

11. ______ tag is an extension to HTML that can enclose any number of JavaScript statements.





12. How does JavaScript store dates in a date object?

A. The number of milliseconds since January 1st, 1970

B. The number of days since January 1st, 1900

C. The number of seconds since Netscape's public stock offering.

D. None of the above

13. Which of the following attribute can hold the JavaScript version?




D. None of the above

14. What is the correct JavaScript syntax to write "Hello World"?

A. System.out.println("Hello World")

B. println ("Hello World")

C. document.write("Hello World")

D. response.write("Hello World")

15. Which of the following way can be used to indicate the LANGUAGE attribute?

A. <LANGUAGE="JavaScriptVersion">

B. <SCRIPT LANGUAGE="JavaScriptVersion">

C. <SCRIPT LANGUAGE="JavaScriptVersion"> JavaScript statements…</SCRIPT>

D. <SCRIPT LANGUAGE="JavaScriptVersion"!> JavaScript statements…</SCRIPT>

16. Inside which HTML element do we put the JavaScript?

A. <js>

B. <scripting>

C. <script>

D. <javascript>

17. What is the correct syntax for referring to an external script called " abc.js"?

A. <script href=" abc.js">

B. <script name=" abc.js">

C. <script src=" abc.js">

D. None of the above

18. Which types of image maps can be used with JavaScript?

A. Server-side image maps

B. Client-side image maps

C. Server-side image maps and Client-side image maps

D. None of the above

19. Which of the following navigator object properties is the same in both Netscape and IE?

A. navigator.appCodeName

B. navigator.appName

C. navigator.appVersion

D. None of the above

20. Which is the correct way to write a JavaScript array?

A. var txt = new Array(1:"tim",2:"kim",3:"jim")

B. var txt = new Array:1=("tim")2=("kim")3=("jim")

C. var txt = new Array("tim","kim","jim")

D. var txt = new Array="tim","kim","jim"

21. What does the <noscript> tag do?

A. Enclose text to be displayed by non-JavaScript browsers.

B. Prevents scripts on the page from executing.

C. Describes certain low-budget movies.

D. None of the above

22. If para1 is the DOM object for a paragraph, what is the correct syntax to change the text within the paragraph?

A. "New Text"?

B. para1.value="New Text";

C. para1.firstChild.nodeValue= "New Text";

D. para1.nodeValue="New Text";

23. JavaScript entities start with _______ and end with _________.

A. Semicolon, colon

B. Semicolon, Ampersand

C. Ampersand, colon

D. Ampersand, semicolon

24. Which of the following best describes JavaScript?

A. a low-level programming language.

B. a scripting language precompiled in the browser.

C. a compiled scripting language.

D. an object-oriented scripting language.

25. Choose the server-side JavaScript object?

A. FileUpLoad

B. Function

C. File

D. Date

26. Choose the client-side JavaScript object?

A. Database

B. Cursor

C. Client

D. FileUpLoad

27. Which of the following is not considered a JavaScript operator?

A. new

B. this

C. delete

D. typeof

28. ______method evaluates a string of JavaScript code in the context of the specified object.

A. Eval

B. ParseInt

C. ParseFloat

D. Efloat

29. Which of the following event fires when the form element loses the focus: <button>, <input>, <label>, <select>, <textarea>?

A. onfocus

B. onblur

C. onclick

D. ondblclick

30. The syntax of Eval is ________________

A. [objectName.]eval(numeric)

B. [objectName.]eval(string)

C. [EvalName.]eval(string)

D. [EvalName.]eval(numeric)

31. JavaScript is interpreted by _________

A. Client

B. Server

C. Object

D. None of the above

32. Using _______ statement is how you test for a specific condition.

A. Select

B. If

C. Switch

D. For

33. Which of the following is the structure of an if statement?

A. if (conditional expression is true) thenexecute this codeend if

B. if (conditional expression is true)execute this codeend if

C. if (conditional expression is true) {then execute this code>->}

D. if (conditional expression is true) then {execute this code}

34. How to create a Date object in JavaScript?

A. dateObjectName = new Date([parameters])

B. Date([parameters])

C. dateObjectName := new Date([parameters])

D. dateObjectName Date([parameters])

35. The _______ method of an Array object adds and/or removes elements from an array.

A. Reverse

B. Shift

C. Slice

D. Splice

36. To set up the window to capture all Click events, we use which of the following statement?

A. window.captureEvents(Event.CLICK);

B. window.handleEvents (Event.CLICK);

C. window.routeEvents(Event.CLICK );

D. window.raiseEvents(Event.CLICK );

37. Which tag(s) can handle mouse events in Netscape?

A. <IMG>

B. <A>

C. <BR>

D. None of the above

38. ____________ is the tainted property of a window object.

A. Pathname

B. Protocol

C. Defaultstatus

D. Host

39. To enable data tainting, the end user sets the _________ environment variable.





40. In JavaScript, _________ is an object of the target language data type that encloses an object of the source language.

A. a wrapper

B. a link

C. a cursor

D. a form

41. When a JavaScript object is sent to Java, the runtime engine creates a Java wrapper of type ___________

A. ScriptObject

B. JSObject

C. JavaObject

D. Jobject

42. _______ class provides an interface for invoking JavaScript methods and examining JavaScript properties.

A. ScriptObject

B. JSObject

C. JavaObject

D. Jobject

43. _________ is a wrapped Java array, accessed from within JavaScript code.

A. JavaArray

B. JavaClass

C. JavaObject

D. JavaPackage

44. A ________ object is a reference to one of the classes in a Java package, such as netscape.javascript .

A. JavaArray

B. JavaClass

C. JavaObject

D. JavaPackage

45. The JavaScript exception is available to the Java code as an instance of __________

A. netscape.javascript.JSObject

B. netscape.javascript.JSException

C. netscape.plugin.JSException

D. None of the above

46. To automatically open the console when a JavaScript error occurs which of the following is added to prefs.js?

A. user_pref(" javascript.console.open_on_error", false);

B. user_pref("javascript.console.open_error ", true);

C. user_pref("javascript.console.open_error ", false);

D. user_pref("javascript.console.open_on_error", true);

47. To open a dialog box each time an error occurs, which of the following is added to prefs.js?

A. user_pref("javascript.classic.error_alerts", true);

B. user_pref("javascript.classic.error_alerts ", false);

C. user_pref("javascript.console.open_on_error ", true);

D. user_pref("javascript.console.open_on_error ", false);

48. The syntax of a blur method in a button object is ______________

A. Blur()

B. Blur(contrast)

C. Blur(value)

D. Blur(depth)

49. The syntax of capture events method for document object is ______________

A. captureEvents()

B. captureEvents(args eventType)

C. captureEvents(eventType)

D. captureEvents(eventVal)

50. The syntax of close method for document object is ______________

A. Close(doc)

B. Close(object)

C. Close(val)

D. Close()

where we use javascript and for which purpose we use
javascript how?
JavaScript was designed to add interactivity to HTML pages
JavaScript is a scripting language
A scripting language is a lightweight programming language
A JavaScript consists of lines of executable computer code
A JavaScript is usually embedded directly into HTML pages
JavaScript is an interpreted language (means that scripts
execute without preliminary compilation)
Everyone can use JavaScript without purchasing a license
JavaScript gives HTML designers a programming tool - HTML
authors are normally not programmers, but JavaScript is a
scripting language with a very simple syntax! Almost anyone
can put small "snippets" of code into their HTML pages
JavaScript can put dynamic text into an HTML page - A
JaDoes javascript support multidimensional arrays ?rmation on the visitor's

How do you send a message to the browser in JavaScript?
Either use (document.write) or use web technology like php
and pass the value through url and get on that page.
What looping structures are there in JavaScript?
FOR, While and Do...While

What does "1"+2+4 evaluate to?
nything which follows string is converted to String.
Hence, "1" is string, and the digits 2 and 4 which comes
after this, also become part of string only.

So the answer is 124

What are the security related issues in JavaScript scripts?
Basically the source code of the Javascript will be visible
when we select the source,hence the javascript part of the
code is fully transparent.
Secondly javascripts can be disabled on the browser easily
Basically all that naveen said is true but there cannot be
any instance of js hiding it can always be viewalble if u
know how to do it.

Also other security issues are that u can track the ip of
the system on which the site has been view also the time of
loading on the current system.

Since javascript has no current standard which monitors the
use of js it can be used in any way you want to.
Therefore security related issues in javascript is just a
idea but never a hard code procedure.

What is the use of a form in html page? Is there any way to submit the page without using the form.

In html we can use JAVASCRIPT for validation purpose. Since
we require a specific form name for validation and to
specicy the action after certain operation is performed.

why you used Java Script? Can it use for both client side and server side validation purpose?
Mainly used for client side scripting purpose.JavaScript is
a platform-independent,event-driven, interpreted client-
side scripting and programming language.

javascript cannot be used as server side scripting.

What is the difference between GET and POST?
A. GET: Parameters are passed in the querystring. Maximum amount of data that can be sent via the GET method is limited to about 2kb.
POST: Parameters are passed in the request body. There is no limit to the amount of data that can be transferred using POST. However, there are limits on the maximum amount of data that can be transferred in one name/value pair.
What is this keyword

The this keyword is a synonym for the current object and can
be used with properties

: How do you convert numbers between different bases in JavaScript?
using parseInt(value,base)
also parseFloat(number,base)

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