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Javascript Interview Questions and Answers
Methods GET and POST in HTML forms -
what's the difference?
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.
How to write a script for "Select" lists using javascript
1. To remove an item from a list set it to null
mySelectObject.options[3] = null;
2. To truncate a list set its length to the maximum size you desire
mySelectObject.length = 2;
3. To delete all options in a select object set the length to 0.
mySelectObject.leng
Text From Your Clipboard?
It is true, text you last copied for pasting (copy & paste) can be
stolen when you visit web sites using a combination of JavaScript and
ASP (or PHP, or CGI) to write your possible sensitive data to a database
on another server.
What does the "Access is Denied" IE error mean?
The "Access Denied" error in any browser is due to the following reason.
A javascript in one window or frame is tries to access another window or
frame whose
document's domain is different from the document containing the script.
Is a javascript script faster than an ASP script?
Yes.Since javascript is a client-side script it does require the web
server's help for its
computation,so it is always faster than any server-side script like
ASP,PHP,etc..
Are Java and JavaScript the Same?
No.java and javascript are two different languages.
Java is a powerful object - oriented programming language like C++,C
whereas Javascript is a
client-side scripting language with some limitations.
How to embed javascript in a web page?
javascript code can be embedded in a web page between <script
langugage="javascript"></script> tags
What and where are the best JavaScript resources on the Web?
The Web has several FAQ areas on JavaScript. The best place to start is
something called the meta-FAQ [14-Jan-2001 Editor's Note: I can't point
to it anymore, it is broken!], which provides a high-level overview of
the JavaScript help available on the Net. As for fact-filled FAQs, I
recommend one maintained by Martin Webb and a mini-FAQ that I maintain.
For interactive help with specific problems, nothing beats the primary
JavaScript Usenet newsgroup, comp.lang.javascript. Depending on my work
backlog, I answer questions posted there from time to time. Netscape and
Microsoft also have vendor-specific developer discussion groups as well
as detailed documentation for the scripting and object model
implementations.
What are the problems associated with using JavaScript, and are there
JavaScript techniques that you discourage?
Browser version incompatibility is the biggest problem. It requires
knowing how each scriptable browser version implements its object model.
You see, the incompatibility rarely has to do with the core JavaScript
language (although there have been improvements to the language over
time); the bulk of incompatibility issues have to do with the object
models that each browser version implements. For example, scripters who
started out with Navigator 3 implemented the image rollover because it
looked cool. But they were dismayed to find out that the image object
wasn't scriptable in Internet Explorer 3 or Navigator 2. While there are
easy workarounds to make this feature work on newer browsers without
disturbing older ones, it was a painful learning experience for many.
The second biggest can of worms is scripting connections between
multiple windows. A lot of scripters like to have little windows pop up
with navigation bars or some such gizmos. But the object models,
especially in the older browser versions, don't make it easy to work
with these windows the minute you put a user in front of them--users who
can manually close windows or change their stacking order. More
recently, a glitch in some uninstall routines for Windows 95
applications can disturb vital parts of the system Registry that
Internet Explorer 4 requires for managing multiple windows. A scripter
can't work around this problem, because it's not possible to detect the
problem in a user's machine. I tend to avoid multiple windows that
interact with each other. I think a lot of inexperienced Web surfers can
also get confused by them.
What Boolean operators does JavaScript support?
&&, || and !
What does "1"+2+4 evaluate to?
Since 1 is a string, everything is a string, so the result is 124.
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