Path: csiph.com!optima2.xanadu-bbs.net!xanadu-bbs.net!feeder.erje.net!1.eu.feeder.erje.net!weretis.net!feeder1.news.weretis.net!news.solani.org!.POSTED!not-for-mail
From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups: comp.lang.javascript
Subject: Re: Retrieve a select from a table cell
Date: Wed, 15 Jul 2015 00:23:38 +0200
Organization: PointedEars Software (PES)
Lines: 68
Message-ID: <5385669.KCYVbj6BcG@PointedEars.de>
References: <mo2utl$9s5$1@dont-email.me> <mo3oq2$qo5$1@speranza.aioe.org> <mo3pud$u2u$1@speranza.aioe.org> <3951517.CJbgAzKFgc@PointedEars.de> <mo3rcn$2h2$1@speranza.aioe.org>
Reply-To: Thomas 'PointedEars' Lahn <cljs@PointedEars.de>
Mime-Version: 1.0
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 8Bit
X-Trace: solani.org 1436912806 14062 eJwFwYkBwEAEBMCWvItyxNF/CZlxBWPC4DA/v23pKKECsINdPrI3dx4VOpYqM19l00tWrh8izRES (14 Jul 2015 22:26:46 GMT)
X-Complaints-To: abuse@news.solani.org
NNTP-Posting-Date: Tue, 14 Jul 2015 22:26:46 +0000 (UTC)
User-Agent: KNode/4.14.2
X-User-ID: eJwFwQUBADAIALBKcDwO2j/CNyFFbWMVZTm5TJeMM+e6xjWqdRyH2BsbqacxPfNsc4C8LJiBTns7HB9/fBsWPA==
Cancel-Lock: sha1:T2ldblxJqE2MrPNtV6t9VLWCLwI=
X-NNTP-Posting-Host: eJwNxsEBwCAIA8CVQEiQdcRm/xHsvQ5B51QSTAha6bQbuLu6hfnLWvqCnbGNDivl0ehEZfUD/9wQMA==
Xref: csiph.com comp.lang.javascript:28424

Joao Rodrigues wrote:

> Em 14/07/2015 17:07, Thomas 'PointedEars' Lahn escreveu:
>> Joao Rodrigues wrote:
>>>   function cellClick(e) {
>>>     var fc = e.target;
>>>     if (/input|select/i.test(fc.tagName)) {
>>>       window.alert(fc.type + " - " + fc.nodeName
>>>                    + " - " + fc.value + " - "
>>>                    + fc.nodeType);
>>>     }
>>>   }
>> 
>> Not only as insufficient as your first approach (see my other follow-up),
> 
> The OP's putclick() function didn't seem to take care of the select's
> options. She just added new selects with the DOMcreasel() function.
> 
>> but even more inefficient and error-prone.  If you are using a regular
>> expression, you need to anchor it to prevent false positives, at least
>> /^(input|select)$/i.
> 
> More efficient, but unnecessary for the test case. Why do you always
> repeat it?

You are not making sense.
 
>> But you can do without such an expensive RegExp here.
> 
> Expensive for modern JavaScript Engines? Nah.

A conforming implementation of ECMAScript Edition 5 and later is required to 
create a new RegExp instance “each time the [/RegularExpressionLiteral/] is 
evaluated”, and “[t]wo regular expression literals in a program evaluate to 
regular expression objects that never compare as === to each other even if 
the two literals’ contents are identical.” (§ 7.8.5).  IOW, any optimization 
is expressly forbidden there.

And if you want to be backwards-compatible, you cannot use non-capturing 
parentheses for the anchored alternation, so each time the match is 
performed memory must be allocated for the backreference.

Add to that the additional runtime for the matcher by comparison to simple 
string comparison.

Besides, it is a misconception to assume that because there are “modern 
JavaScript engines” the algorithms underlying one’s ECMAScript-based script 
code would not need to be efficient.  Because one cannot know in advance all 
runtime environments one’s code will be exposed to.

>> Finally, the “input” appears to be coming from your imagination only;
>> read again.
> 
> You should read again as you have forgotten the HTML table in the OP's
> code:
> 
> | <TD><INPUT type='checkbox' name='chk'/></TD>
> | <TD><INPUT type='text' name='txt'/></TD>

The OP is evidentially not interested in the values of these controls: Both 
the Subject header field value and their posting reads “Retrieve a *select* 
from a table cell” (emphasis by me).
 
-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | SVN: <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | ES Matrix: <http://PointedEars.de/es-matrix>
Please do not cc me. / Bitte keine Kopien per E-Mail.