comp.lang.javascript FAQ - META - 9.88 - 2007-10-12
1 meta-FAQ meta-questions
2 comp.lang.javascript tips
2.1 Which newsgroups deal with javascript?
2.2 What questions are off-topic for clj?
2.3 What do I have to do before posting to clj?
2.4 Why was my post not answered?
2.5 How do I direct someone to this FAQ?
2.6 What is ECMAScript?
2.7 What is JScript?
2.8 What are object models?
2.9 What is the do***ent object model?
2.10 Internationalization and Multinationalization in javascript.
2.11 I have a question that is not answered in here or
in any of the resources mentioned here but I'm sure it has been
answered in clj. Where are the clj archives located?
2.12 What does the future hold for ECMAScript?
3 javascript resources
3.1 What books cover javascript?
3.2 What online resources are available?
4 Quick Answers
4.1 How do I protect my javascript code?
4.2 How can I disable the back button in a web browser?
4.3 How can I access the client-side filesystem?
4.4 How can I see in javascript if a web browser accepts cookies?
4.5 How can I prevent access to a web page by using javascript?
4.6 How do I convert a Number into a String with exactly 2 decimal
places?
4.7 Why does simple decimal arithmetic give strange results?
4.8 How do I communicate between frames in a web browser?
4.9 How do I find the size of the window/browser canvas area?
4.10 How do I check to see if a childwindow is open, before opening
another?
4.11 Why does framename.print() not print the correct frame in IE?
4.12 Why does K = parseInt('09') set K to 0?
4.13 How do I get the value of a form control?
4.14 How do I close a window and why does it not work on the first one?
4.15 How do I modify the current page in a browser?
4.16 How do I trim whitespace - LTRIM/RTRIM/TRIM?
4.17 How do I force a reload from the server/prevent caching?
4.18 How do I get a perl/asp/php variable into client-side js?
4.19 Why do I get permission denied when accessing a frame/window?
4.20 How do I make a 10 second delay?
4.21 Why does 1+1 equal 11? or How do I convert a string to a number?
4.22 How do I generate a random integer from 1 to N?
4.23 How do I change print settings with window.print()?
4.24 I have <a href="javascript:somefunction()"> what ... ?
4.25 My element is named myselect[] , how do I access it?
4.26 How do I detect Opera/Netscape/IE?
4.27 How do I disable the right mouse button?
4.28 How do I change the confirm box to say yes/no or default to cancel?
4.29 How do I log-out a user when they leave my site?
4.30 How do I format the Last-Modified date with javascript?
4.31 Why are my rollovers so slow?
4.32 How do I change the text in the url/location bar?
4.33 How do I prompt a "Save As" dialog for an accepted mime type?
4.34 How do I run a server side script?
4.35 I have window.status="Moomin"; why doesn't the statusbar change?
4.36 How do I modify the current browser window?
4.37 How do I POST a form to a new window?
4.38 How do I download a page to a variable?
4.39 How do I access a property of an object using a string?
4.40 When should I use eval?
4.41 Why doesn't the global variable "divId" always refer to the element
with id="divId"?
4.42 How do I open a new window with javascript?
4.43 How do I get my browser to re****t javascript errors?
4.44 What is AJAX?
4.45 Why is my AJAX page not updated properly when using an HTTP GET
request in Internet Explorer?
5 Comments and Suggestions
5.1 Why do some posts have <FAQENTRY> in them ?
5.2 How do I make a suggestion?
1 meta-FAQ meta-questions
You are reading the _comp.lang.javascript_ meta-FAQ,
version 9.88. It is available on the web at
<URL: http://www.jibbering.com/faq/index.html
> in HTML form.
This is the official _comp.lang.javascript_ (clj) FAQ.
Or, more accurately, the meta-FAQ. It mainly provides URLs to
further information about javascript, and some hints and tips to
make your stay in comp.lang.javascript more enjoyable.
This do***ent was created for three reasons: to help reduce the
high levels of noise on clj, to provide a resource for people
new to javascript, and to point to locations that contain
valuable javascript resources.
Each day, one section of the FAQ is posted for review and questions,
and as a reminder that the FAQ is available.
To cope with a desire for additional explanation and detail
relating to some aspects of the FAQ, an additional resource
is available at:-
<URL: http://www.jibbering.com/faq/faq_notes/faq_notes.html
>
It has been provided separately to avoid increasing the size of
the FAQ to a point where it would be unreasonable to post it to
the group.
2 comp.lang.javascript tips
2.1 Which newsgroups deal with javascript?
The official Usenet newsgroup dealing with javascript is
news:comp.lang.javascript. There are other newsgroups but many of
them are not carried by most news feeds. clj is an unmoderated
newsgroup.
2.2 What questions are off-topic for clj?
The comp.lang.javascript newsgroup deals with ECMAScript
languages, so any questions about JavaScript or JScript are
welcome. However, the majority of questions sent to this group
relates to javascript in a web browser. If you are experiencing
issues with a particular browser, or the host is not a browser
at all, please make this information clear.
Javascript and Java are two completely different languages.
Java questions should be asked in one of the comp.lang.java.*
newsgroups; they are not appropriate for clj (as Java and
javascript are distinct programming languages with only
superficial similarities due to sharing a C-like syntax and
some of the characters in their names).
Questions dealing with other scripting languages, such as
VBScript, PerlScript or CGI scripting are also off-topic,
as are HTML-only or CSS-only questions.
Questions that are specific to Microsoft's JScript may also
be appropriately asked at:
news:microsoft.public.scripting.jscript
The comp.lang.javascript newsgroup charter is included in
<URL: http://www.jibbering.com/faq/faq_notes/cljs_charter.html
>
2.3 What do I have to do before posting to clj?
Before posting to clj, you should thoroughly read this do***ent.
You should also check the resources mentioned in section 3 and
the Quick Answers in section 4. Read FYI28/RFC1855
<URL: http://www.ietf.org/rfc/rfc1855.txt
> on Usenet and
<URL: http://www.jibbering.com/faq/faq_notes/clj_posts.html
>.
Also you should read all appropriate posts to the clj newsgroup
for several days. Most questions come up at least once every
other day and people can get annoyed of answering them
repeatedly.
Please state your question as clearly and concisely as possible,
as this will make it far easier for the other readers of the
group to understand your problems and suggest possible solutions.
Use the Subject: of your post to indicate the type of problem
you have, but include the question in the body as well. 'Help!'
or 'I hate Netscape!' are not nearly as useful to contributors
who do not read every post as 'parseInt("09")!=9'.
Has the same question already been posted that day? - if it has
wait to see if the answers to that solve your problem.
Include the script you have been working on (or URL) - indicate
the problem spots and/or previous attempts. Try to limit the
length of your post by removing extraneous page elements, but
avoid removing script unless you are sure it is not an issue. If
the script is long though, please do not post the full script
and just provide a link. As a guide more than 500 lines for a
post is not normally a good idea in any cir***stances. A
mention of which platforms and browsers are used or are giving
problems is also necessary.
Post in plain-text only. Do not post using HTML. If you have to
include your script, paste it in to your post in plain-text. Do
not uuencode it or attach it using MIME. There is good reason for
this request: many newsreaders do not read HTML or MIME, and this
limits the number of people who could help you. Test posts belong
in test newsgroups (they have "test" in their names).
Make sure your code is executable as transmitted. Use line breaks
to keep the posting agent from wrapping code incorrectly.
When replying to a message on the group quote the minimum of the
preceding messages that is sufficient to provide context for
the reply but trim the remainder, and add your comments below the
pertinent section of quoted material, as per FYI28/RFC1855 (never
top post).
Don't ask, or at least expect, to be emailed individually. Some
individuals run scams for the purpose of collecting active email
addresses and many won't risk being victimized. If you have
cir***stances that won't allow you to read clj for the
follow-up, explain what they are and ask to be CC'ed a copy. You
also might try <URL:
http://groups.google.com/group/comp.lang.javascript/topics
> to read
replies.
Don't expect to be able to e-mail contributors to the group
privately. E-mail addresses are often obscured, fictional or
unmonitored spam sinks (this is an increasingly normal (and
even unofficially recommended) practice as open e-mail
addresses in news articles will be both the target of spam
and used as fake sender's addresses in spam to third parties).
Don't take flames too seriously, and don't start a thread
complaining about rude or flippant responses. There is already
enough noise in clj. Keep a sense of humour while posting and
reading and everything will be a lot more enjoyable.
Remember that it is _not_ the _job_ of posters
here to help you. The majority of regular posters here do so
_voluntarily_ in their free time. They have good days
and bad days just like everyone else.
clj is a technical group: the posting of job adverts and
commercial adverts are not welcome. Job postings should go to
an appropriate regional jobs group. Announcements of products
of particular relevance to javascript are welcome, but not
more often than once per major release, and then post a short
link to the product's webpage.
Please do not post copyrighted material to clj without permission
from the copyright holder.
2.4 Why was my post not answered?
This could be for several reasons:
It was a variation of a frequently asked question and was
therefore ignored by everyone.
Nobody knows the answer.
The person with the answer has not seen the post.
It might not be possible to do what you want to do but perhaps
readers of clj are reluctant to answer your post in the negative
when they are not convinced that it cannot be done.
The question was not asked clearly enough, or did not included
enough information to be answered.
The questioner did not realise the need to read the group, for a
few days, to see the answers posted there.
If it is not one of these, then after a few days consider
reposting after checking <URL:
http://groups.google.com/group/comp.lang.javascript/topics
>
for replies. Make sure the post is phrased well, and everything
needed to answer is correct, and the subject is appropriate.
2.5 How do I direct someone to this FAQ?
This do***ent is posted to clj very frequently. There should be
no reason to direct someone to it. However, if someone asks a
question answered in this FAQ or in one of the resources listed
herein, please let them know their question is answered in the
FAQ and that the FAQ can be found at
<URL: http://www.jibbering.com/faq/
>
2.6 What is ECMAScript?
<URL:
http://www.ecma-international.org/publications/standards/Ecma-262.htm
>
ECMAScript is the international standard for javascript. JScript
3.0 and JavaScript 1.2 (available with version 4. browsers) are
more or less ECMAScript compliant. In addition ECMA 327 defines
the Compact Profile of ECMAScript by describing the features from
ECMA 262 that may be omitted in some resource-constrained
environments. Note that ECMAScript did not attempt to standardize
the do***ent object model.
The current edition is ECMA-262, 3rd Edition. There is some
sup****t for this edition in JScript 5.0 and JavaScript 1.3.
JScript 5.5 and JavaScript 1.5, in Netscape 6.1 and later, are
compliant (JavaScript 1.5 in Netscape 6 missed some methods).
2.7 What is JScript?
JScript is Microsoft's implementation of ECMAScript.
Questions that are specific to Microsoft's JScript may also
be appropriately asked at:
news:microsoft.public.scripting.jscript
2.8 What are object models?
Object models (OMs) are not part of the javascript language: they
are provided by the host to allow javascript (or other scripting
language) to communicate with the host. An object model may allow
javascript to access a file system, or control a nuclear power
station. The most commonly used object models via javascript are
provided by Active Server Pages, Server Side JavaScript, and the
Windows Script Host. The most common of all is the
Do***ent Object Model (DOM) provided by web browsers. Other
do***ent types such as SVG also define scriptable DOMs, mostly as
extensions of the W3C Core DOM specification designed for use
with XML do***ents.
2.9 What is the do***ent object model?
This is the collection of objects provided by each browser.
Basically, any object in the window hierarchy is part of the
DOM. This means that do***ent.writeln(), for example, is not a
javascript method but is, in fact, a method provided by the DOM.
The DOM has been standardised by the World Wide Web Consortium
(W3C); however, like all W3C standards, browser sup****t is not
yet complete. Most cross-browser coding problems come from
slightly different implementations of the DOM in the different
browsers.
W3 DOM FAQ <URL: http://www.w3.org/DOM/faq.html
>
The W3C has worked on three versions of the DOM to date. The
third version has not yet achieved the status of a
recommendation <URL: http://www.w3.org/DOM/
>.
2.10 Internationalization and Multinationalization in javascript.
Internationalisation means using one form which is everywhere both
acceptable and understood. Any international standard not sup****ted
by
default can be coded for.
For example, there is an International Standard for numeric
Gregorian
date format; but none for decimal and thousands separators.
Multinationalisation means using different forms for different
readers. It cannot work well in general, because it requires a
knowledge of all preferences and the ability to choose the right
one, in an environment where many systems are inappropriately
set anyway.
JavaScript has a few Multinationalisation features. The various
toString() methods are all implementation dependent, but tend to
use either UK or US settings (not necessarily correctly). ECMAScript
Ed. 3 introduced some capabilities, including the toLocaleString()
method which should create a string based on the host's locale.
Much more sup****t is expected in future versions of JavaScript.
2.11 I have a question that is not answered in here or
in any of the resources mentioned here but I'm sure it has been
answered in clj. Where are the clj archives located?
<URL: http://groups.google.com/group/comp.lang.javascript/topics
>
Maintain an archive of comp.lang.javascript going back to 1996 and
provide diverse archive searching facilities.
2.12 What does the future hold for ECMAScript?
The ECMAScript Technical Committee is now working on the fourth
edition, the first implementation of which is JScript.NET. It
includes a compiler, allowing you to create standalone JScript
executables.
The fourth edition of ECMAScript will provide new features like
typed variables, and cl*****. More information can be found at:
<URL: http://www.mozilla.org/js/language/es4/index.html
>,
or from news:microsoft.public.dotnet.languages.jscript
3 javascript resources
3.1 What books cover javascript?
Most clj regulars believe the best book to be:
JavaScript: The Definitive Guide, 5th Edition By David Flanagan
ISBN:0-596-10199-6
The errata should be considered a must read along with the book.
<URL: http://www.oreilly.com/catalog/jscript5/
>
Errata:
<URL: http://www.oreilly.com/catalog/jscript5/errata/
>
3.2 What online resources are available?
The official ECMAScript specification:-
<URL:
http://www.ecma-international.org/publications/standards/Ecma-262.htm
>
Other versions of the ECMAScript specification:-
<URL: http://www.mozilla.org/js/language/
>
DOM level 1 ECMA script binding:-
<URL:
http://www.w3.org/TR/REC-DOM-Level-1/ecma-script-language-binding.html
>
DOM level 2 ECMA script binding:-
<URL: http://www.w3.org/TR/DOM-Level-2-HTML/ecma-script-binding.html
>
Mozilla JavaScript 1.5 reference:-
<URL: http://developer.mozilla.org/en/docs/JavaScript
>
Online Gecko DOM Reference:-
<URL: http://developer.mozilla.org/en/docs/Gecko_DOM_Reference
>
Download:-
<URL: http://www.mozilla.org/docs/dom/domref.zip
>
Microsoft (D)HTML reference:-
<URL:
http://msdn.microsoft.com/workshop/author/dhtml/reference/dhtml_reference_entry.asp
>
JScript reference and main Microsoft script site:-
<URL:
http://msdn.microsoft.com/library/en-us/script56/html/1e9b3876-3d38-4fd8-8596-1bbfe2330aa9.asp
>
<URL: http://msdn.microsoft.com/scripting/
>
Opera Do***entation:-
<URL: http://www.opera.com/docs/specs/#ecmascript
>
<URL: http://www.opera.com/docs/specs/js/
>
ICab's Inscript do***entation:-
<URL: http://www.muchsoft.com/inscript/
>
Frequently asked questions about source code obfuscation:-
<URL: http://jibbering.com/faq/obfuscate.html
>
Microsoft Script Debugger Do***entation:
<URL: http://msdn.microsoft.com/library/en-us/sdbug/Html/sdbug_1.asp
>
Venkman - Mozilla Visual JS debugger:-
<URL: http://www.mozilla.org/projects/venkman/
>
Firebug extension for Firefox:-
<URL: http://www.getfirebug.com/
>
Index of Netscape 4 JavaScript docs online (These do***ents are no longer
available form Netscape but are still reproduced by Sun Microsystems,
Inc.):-
<URL: http://docs.sun.com/source/816-6408-10/
>
Index of Archived Netscape 4 JavaScript docs online and for download:-
<URL:
http://devedge-temp.mozilla.org/library/manuals/2000/javascript/1.3/reference/
>
Archived do***entation for MSIE 3.x:-
<URL: http://members.tripod.com/~housten/download/
>
Javascript FAQ site:-
<URL: http://javascript.faqts.com/
>
FESI - a free implementation of ECMAScript in Java:-
<URL: http://www.lugrin.ch/fesi/index.html
>
Sites discussing Active Server Pages:-
<URL: http://www.15seconds.com/
>
<URL: http://www.4guysfromrolla.com/
>
<URL: http://www.aspfaq.com/
>
DHTML source code and tutorials:-
<URL: http://www.w3schools.com/
>
Sites focused on using Scripting to automate Windows:-
<URL: http://www.windows-script.com/
>
<URL: http://cwa****ngton.netreach.net/
>
Microsoft's Windows Scripting Host (WSH) Newsgroup:-
Microsoft's JScript Newsgroup:-
Whitebeam Apache Module - Server Side Javascript in Apache;-
<URL: http://www.whitebeam.org/
>
Digital Mars DMD Script, console and MS Active Script implementation of
ECMAScript, claimed to be faster than other implementations:-
<URL: http://www.digitalmars.com/dscript/
>
4 Quick Answers
see <URL: http://jibbering.com/faq/#FAQ4
>
Or Mondays FAQ posting.
5 Comments and Suggestions
5.1 Why do some posts have <FAQENTRY> in them ?
If a poster feels that the question they are answering should be
covered in the FAQ, placing <FAQENTRY> in your post lets the FAQ
robot collect the messages for easy review and inclusion. A Draft
Proposal
for the FAQ is requested and appreciated.
The <FAQENTRY> should not be used in posts except in
conjunction with a suggestion/proposal for the FAQ. It should
also not be literally quoted in replies, instead it should be
partly obscured as, e.g. <FAQ**TRY> or similar.
5.2 How do I make a suggestion?
To make a suggestion to the FAQ, use either the FAQENTRY method
above, or email Randy Webb (cljfaq@[EMAIL PROTECTED]
) (current FAQ editor)
or Jim Ley (jim.ley@[EMAIL PROTECTED]
). All comments, suggestions, and
especially corrections are welcome. Any email sent to
cljfaq@[EMAIL PROTECTED]
that does not contain FAQENTRY in the subject line is summarily
deleted
by my spam filter.
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