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Groups > comp.lang.javascript > #29382
| From | Thomas 'PointedEars' Lahn <PointedEars@web.de> |
|---|---|
| Newsgroups | comp.lang.javascript |
| Subject | Re: Give alert if form checkbox array is empty |
| Date | 2016-01-21 00:59 +0100 |
| Organization | PointedEars Software (PES) |
| Message-ID | <1851504.v7CTRd67sv@PointedEars.de> (permalink) |
| References | <d5vt9b95kifj8nb7phn75pl16tpijop14s@4ax.com> <n7njvu$51k$1@news.albasani.net> <mu00ablmp9s6ronvrrejt2npfp5uffhpc5@4ax.com> |
Bunyip wrote:
^^^^^^
Please post using your full (real) name.
> On Wed, 20 Jan 2016 10:28:29 +0100, Stefan Weiss
> <krewecherl@gmail.com> wrote:
>>var subjectTypes = document.getElementsByName('subjectType[]');
>>for (var i = 0; i < subjectTypes.length; i++) {
>> if (subjectTypes[i].checked) {
>>
> Many thanks, Stefan. This worked:
>
> var subjectTypes = document.getElementsByName('subjectType[]');
The disadvantage of using “document.getElementsByName()” over (here) the
“form.elements” collection is that the former applies to all names in the
document, while the latter only applies to the controls of that specific
form. As as result, the latter is not only more efficient, but also less
error-prone.
Also, since the reference to the form element object is available in the
event-handler attribute and in the listener with “this” (unless you unwisely
use attachEvent()), the latter can be made to work regardless of the form
name or position in the document.
> var STchecked;
Names should not start with a capital letter unless the value of the
variable/property is intended to be a reference to a constructor.
> for (var i = 0; i < subjectTypes.length; i++) {
for (var i = 0, len = subjectTypes.length; i < len; i++) {
But make sure that you do not modify “len” elsewhere.
> if (subjectTypes[i].checked) {
> STchecked = 1;
> break;
> }
You should familiarize yourself with the Array methods introduced with
implementations of ECMAScript Edition 5 at the latest, in order to not write
explicit loops where they are not necessary. Examples have been given.
Keep in mind that the built-in implementation of an algorithm is naturally
always the most efficient one to use as it is, at best, provided in machine
code already.
> }
> if (!STchecked){
> alert("Please enter the subject type");
Again, do not use alert(); update the form instead. In this case, the
“fieldset” element for the checkbox group could be highlighted.
> form.focus();
Pointless. The form already receives the focus once the alert message is
closed, since it had the focus when it was submitted. You should focus the
offending form control instead.
--
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.
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Give alert if form checkbox array is empty Bunyip <bunyip@koalanet.com.au> - 2016-01-20 13:28 +1000
Re: Give alert if form checkbox array is empty JJ <jj4public@vfemail.net> - 2016-01-20 12:30 +0700
Re: Give alert if form checkbox array is empty Bunyip <bunyip@koalanet.com.au> - 2016-01-20 17:55 +1000
Re: Give alert if form checkbox array is empty JJ <jj4public@vfemail.net> - 2016-01-20 19:29 +0700
Re: Give alert if form checkbox array is empty "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-01-20 13:46 +0100
Re: Give alert if form checkbox array is empty Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2016-01-20 08:23 +0000
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-20 15:52 +0100
Re: Give alert if form checkbox array is empty Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2016-01-20 15:43 +0000
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-20 17:15 +0100
Re: Give alert if form checkbox array is empty Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-01-20 17:53 +0000
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-20 20:39 +0100
Re: Give alert if form checkbox array is empty Jon Ribbens <jon+usenet@unequivocal.co.uk> - 2016-01-20 22:46 +0000
Re: Give alert if form checkbox array is empty Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2016-01-21 07:53 +0000
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-21 10:52 +0100
Re: Give alert if form checkbox array is empty Cezary Tomczyk <cezary.tomczyk@gmail.com> - 2016-01-21 10:26 +0000
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-22 00:07 +0100
Re: Give alert if form checkbox array is empty Stefan Weiss <krewecherl@gmail.com> - 2016-01-20 10:28 +0100
Re: Give alert if form checkbox array is empty Bunyip <bunyip@koalanet.com.au> - 2016-01-21 08:05 +1000
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-21 00:59 +0100
Re: Give alert if form checkbox array is empty Stefan Weiss <krewecherl@gmail.com> - 2016-01-21 03:17 +0100
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-21 08:54 +0100
Re: Give alert if form checkbox array is empty Stefan Weiss <krewecherl@gmail.com> - 2016-01-21 12:17 +0100
Re: Give alert if form checkbox array is empty John Harris <niam@jghnorth.org.uk.invalid> - 2016-01-21 14:16 +0000
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-21 19:52 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-22 09:48 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-22 10:45 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-23 19:41 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-24 17:51 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-25 19:46 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-27 11:09 -0800
Re: Give alert if form checkbox array is empty Dr J R Stockton <reply1600@merlyn.demon.co.uk.invalid> - 2016-01-23 22:22 +0000
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-27 11:06 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-28 14:46 +0100
Re: Give alert if form checkbox array is empty Gene Wirchenko <genew@telus.net> - 2016-01-28 10:30 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-28 20:06 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-28 23:32 -0800
Re: Give alert if form checkbox array is empty "Evertjan." <exxjxw.hannivoort@inter.nl.net> - 2016-01-29 09:05 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-29 06:02 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-29 20:54 +0100
Re: Give alert if form checkbox array is empty John Harris <niam@jghnorth.org.uk.invalid> - 2016-01-29 10:36 +0000
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-02-09 04:39 +0100
Re: Give alert if form checkbox array is empty John Harris <niam@jghnorth.org.uk.invalid> - 2016-02-09 18:07 +0000
Re: Give alert if form checkbox array is empty Gene Wirchenko <genew@telus.net> - 2016-01-29 09:32 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-29 20:34 +0100
Re: Give alert if form checkbox array is empty Aleksandro <aleksandro@gmx.com> - 2016-01-29 16:50 -0300
Re: Give alert if form checkbox array is empty Stefan Weiss <krewecherl@gmail.com> - 2016-01-30 03:31 +0100
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-30 04:19 +0100
Re: Give alert if form checkbox array is empty Stefan Weiss <krewecherl@gmail.com> - 2016-01-30 05:01 +0100
Re: Give alert if form checkbox array is empty Aleksandro <aleksandro@gmx.com> - 2016-01-28 16:39 -0300
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-29 06:04 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-29 20:54 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-29 14:55 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-30 04:55 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-30 15:48 -0800
Re: Give alert if form checkbox array is empty Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2016-01-31 21:02 +0100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-01-31 13:08 -0800
Re: Give alert if form checkbox array is empty Andrew Poulos <ap_prog@hotmail.com> - 2016-02-01 12:28 +1100
Re: Give alert if form checkbox array is empty Scott Sauyet <scott.sauyet@gmail.com> - 2016-02-01 17:58 -0800
Re: Give alert if form checkbox array is empty "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2016-01-20 06:25 -0800
Re: Give alert if form checkbox array is empty Aleksandro <aleksandro@gmx.com> - 2016-01-20 12:54 -0300
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