Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > comp.lang.javascript > #38077 > unrolled thread

Re: Isalpha, isalnum in Javascript?

Back to article view | Back to comp.lang.javascript

This discussion starts older than the indexed window; earlier articles aren't shown. The article labeled Started by below is the oldest one visible, not the original post.

Contents

  Re: Isalpha, isalnum in Javascript? ms.2052001@gmail.com - 2020-01-17 00:50 -0800
    Re: Isalpha, isalnum in Javascript? JJ <jj4public@vfemail.net> - 2020-01-17 23:05 +0700
      Re: Isalpha, isalnum in Javascript? dr.j.r.stockton@gmail.com - 2020-01-17 13:07 -0800
        Re: Isalpha, isalnum in Javascript? JJ <jj4public@vfemail.net> - 2020-01-18 21:01 +0700
          Re: Isalpha, isalnum in Javascript? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2020-01-18 19:13 +0100
    Re: Isalpha, isalnum in Javascript? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2020-01-17 21:10 +0000
      Re: Isalpha, isalnum in Javascript? dr.j.r.stockton@gmail.com - 2020-01-18 02:42 -0800
        Re: Isalpha, isalnum in Javascript? JJ <jj4public@vfemail.net> - 2020-01-18 21:01 +0700
        Re: Isalpha, isalnum in Javascript? "Michael Haufe (TNO)" <tno@thenewobjective.com> - 2020-01-18 12:13 -0800
      Re: Isalpha, isalnum in Javascript? Julio Di Egidio <julio@diegidio.name> - 2020-01-19 10:07 -0800
        Re: Isalpha, isalnum in Javascript? dr.j.r.stockton@gmail.com - 2020-01-19 15:39 -0800
          Re: Isalpha, isalnum in Javascript? Julio Di Egidio <julio@diegidio.name> - 2020-01-19 15:45 -0800

#38077 — Re: Isalpha, isalnum in Javascript?

On Friday, 2 January 1998 10:00:00 UTC+2, A.P.  wrote:
> Hello,
> I would like to know if there's a way to check if a character is
> alphanumeric or if it belongs to a certain class of characters without
> having to check explicitly for all the cases with an endless if. I've
> tried with character>='A' and also with the Ascii code but I had no
> success.
> Please answer to my mailbox too. Thank you very much in advance.


You can use regex expressions to check, but it will check for English letters,
code: 
var isAlpha = (c) => (/[A-Za-z]/).test(c);

[toc] | [next] | [standalone]

#38078

On Fri, 17 Jan 2020 00:50:09 -0800 (PST), ms.2052001@gmail.com wrote:
> On Friday, 2 January 1998 10:00:00 UTC+2, A.P.  wrote:
>> Hello,
>> I would like to know if there's a way to check if a character is
>> alphanumeric or if it belongs to a certain class of characters without
>> having to check explicitly for all the cases with an endless if. I've
>> tried with character>='A' and also with the Ascii code but I had no
>> success.
>> Please answer to my mailbox too. Thank you very much in advance.
> 
> You can use regex expressions to check, but it will check for English letters,
> code: 
> var isAlpha = (c) => (/[A-Za-z]/).test(c);

I taut I taw a millennial.

[toc] | [prev] | [next] | [standalone]

#38079

On Friday, 17 January 2020 16:05:20 UTC, JJ  wrote:
> On Fri, 17 Jan 2020 00:50:09 -0800 (PST), ms.2052001#gmail.com wrote:
> > On Friday, 2 January 1998 10:00:00 UTC+2, A.P.  wrote:
> >> Hello,
> > ...
> > var isAlpha = (c) => (/[A-Za-z]/).test(c);
> 
> I taut I taw a millennial.

Indeed.  The answers given might have been reasonable in those far-off days, but appear inadequate now, except for those who believe that the only real characters are those on the keyboard of an American PC.

ISTM that Java has a Character entity, with methods such as Character.getType(), and that Java can access many sorts of information about characters which we here could write as \u0000 to \uFFFF - and higher.

So : what information can modern JavaScript obtain about Unicode characters such as the single characters `xi` and `XI` and strange characters existing in Eastern alphabets such as Danish, Russian, Japanese ... ?


-- 
  (c) John Stockton, near London, UK.  Using Google Groups.           |
 Mail: J.R.""""""""@physics.org - or as Reply-To, if any.             |

[toc] | [prev] | [next] | [standalone]

#38083

On Fri, 17 Jan 2020 13:07:27 -0800 (PST), dr.j.r.stockton@gmail.com wrote: 
> 
> So : what information can modern JavaScript obtain about Unicode
> characters such as the single characters `xi` and `XI` and strange
> characters existing in Eastern alphabets such as Danish, Russian,
> Japanese ... ?

Only the code point.

[toc] | [prev] | [next] | [standalone]

#38084

JJ wrote:

> On Fri, 17 Jan 2020 13:07:27 -0800 (PST), dr.j.r.stockton@gmail.com wrote:
>> So : what information can modern JavaScript obtain about Unicode
>> characters such as the single characters `xi` and `XI` and strange
>> characters existing in Eastern alphabets such as Danish, Russian,
>> Japanese ... ?
> 
> Only the code point.

Much more after reading in the Unicode Character Database (BTDT in my JSX, 
see UnicodeData.js, UnicodeData.txt, and jsx.regexp.RegExp in regexp.js):

<http://www.unicode.org/ucd/>

<https://stackoverflow.com/a/8568325/855543> (my answer in 2011)

-- 
PointedEars
FAQ: <http://PointedEars.de/faq> | <http://PointedEars.de/es-matrix>
<https://github.com/PointedEars> | <http://PointedEars.de/wsvn/>
Twitter: @PointedEars2 | Please do not cc me./Bitte keine Kopien per E-Mail.

[toc] | [prev] | [next] | [standalone]

#38080

ms.2052001@gmail.com writes:

> On Friday, 2 January 1998 10:00:00 UTC+2, A.P.  wrote:
>> Hello,
>> I would like to know if there's a way to check if a character is
>> alphanumeric or if it belongs to a certain class of characters without
>> having to check explicitly for all the cases with an endless if. I've
>> tried with character>='A' and also with the Ascii code but I had no
>> success.
>> Please answer to my mailbox too. Thank you very much in advance.
>
>
> You can use regex expressions to check, but it will check for English letters,
> code: 
> var isAlpha = (c) => (/[A-Za-z]/).test(c);

If you have ECMAScript 9, you can use

  /\p{Letter}/u

as the pattern to match all Unicode characters with property
General_Category = Letter.  Still not 100%, but it might be what's wanted.

-- 
Ben.

[toc] | [prev] | [next] | [standalone]

#38081

On Friday, 17 January 2020 21:10:12 UTC, Ben Bacarisse  wrote:

> If you have ECMAScript 9, you can use

Well, yes, but for Web authors the need must be for the readers to have ECMAscript 9.


>   /\p{Letter}/u
> 
> as the pattern to match all Unicode characters with property
> General_Category = Letter.  Still not 100%, but it might be what's wanted.

My up-to-date Firefox 72.0.1 (64-bit) then appears not to have ECMAScript 9.  Is there now a way in ECMAScript to determine the ECMAScript version number?

H'mm - if there is such a way, it would be necessary, I suppose, to use the above RegExp within try...catch, and compose a moderately graceful failure.

-- 
  (c) John Stockton, near London, UK.  Using Google Groups.           |
 Mail: J.R.""""""""@physics.org - or as Reply-To, if any.             |

[toc] | [prev] | [next] | [standalone]

#38082

On Sat, 18 Jan 2020 02:42:22 -0800 (PST), dr.j.r.stockton@gmail.com wrote: 
> 
> My up-to-date Firefox 72.0.1 (64-bit) then appears not to have ECMAScript
> 9.  Is there now a way in ECMAScript to determine the ECMAScript version
> number? 

Probably not.

> H'mm - if there is such a way, it would be necessary, I suppose, to use
> the above RegExp within try...catch, and compose a moderately graceful
> failure.

It can be determined by checking feature presence and/or functionalities.

[toc] | [prev] | [next] | [standalone]

#38086

On Saturday, January 18, 2020 at 4:42:29 AM UTC-6, dr.j.r...@gmail.com wrote:
> On Friday, 17 January 2020 21:10:12 UTC, Ben Bacarisse  wrote:
> 
> > If you have ECMAScript 9, you can use
> 
> Well, yes, but for Web authors the need must be for the readers to have ECMAscript 9.


There is a babel plugin for this:

<https://babeljs.io/docs/en/next/babel-plugin-proposal-unicode-property-regex.html>

with an example:

<https://mothereff.in/regexpu#input=var+regex+%3D+/%5Cp%7BScript_Extensions%3DGreek%7D/u%3B&unicodePropertyEscape=1>

[toc] | [prev] | [next] | [standalone]

#38095

On Friday, 17 January 2020 22:10:12 UTC+1, Ben Bacarisse  wrote:
> ms.2052001@gmail.com writes:
> > On Friday, 2 January 1998 10:00:00 UTC+2, A.P.  wrote:
> >> Hello,
> >> I would like to know if there's a way to check if a character is
> >> alphanumeric or if it belongs to a certain class of characters without
> >> having to check explicitly for all the cases with an endless if. I've
> >> tried with character>='A' and also with the Ascii code but I had no
> >> success.
> >> Please answer to my mailbox too. Thank you very much in advance.
> >
> > You can use regex expressions to check, but it will check for English letters,
> > code: 
> > var isAlpha = (c) => (/[A-Za-z]/).test(c);

You would use Unicode code points in character ranges, as in the last
example here:
<https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions/Character_Classes>

> If you have ECMAScript 9, you can use
> 
>   /\p{Letter}/u

If all you have is a hammer...

> as the pattern to match all Unicode characters with property
> General_Category = Letter.  Still not 100%, but it might be what's
> wanted.

LOL.  Haven't you and the others noticed that you are replying to a thread
from 1998?  As far as I remember, at the time JS didn't have RegExp at all,
and even a quite limited support (certainly browser-wise) for Unicode in
strings: which is the reason for that question...

Julio

[toc] | [prev] | [next] | [standalone]

#38104

On Sunday, 19 January 2020 18:07:34 UTC, Julio Di Egidio  wrote:


> LOL.  Haven't you and the others noticed that you are replying to a thread
> from 1998?

One does not reply to a thread; one replies to an article.  My first article in the thread was only technically a Reply; in essence, it proposed renewing the question.


> As far as I remember, at the time JS didn't have RegExp at all,
> and even a quite limited support (certainly browser-wise) for Unicode in
> strings: which is the reason for that question...

That may depend on which parts of 1998 you remember.

I am holding David Flanagan's JavaScript Pocket Reference, First Edition, October 1998.  Its Object Reference part includes a RegExp section (Availability, Core JavaScript 1.2), and its description of the String Data Type says that ECMA-262 requires support of full 16-bit Unicode.

It does say that IE4 supports Unicode but Navigator 4 does not.

His Definitive Guide, 3rd Edn, says much the same, at greater length; the Preface is dated April 1998, publication June 1998.


-- 
  (c) John Stockton, near London, UK.  Using Google Groups.           |
 Mail: J.R.""""""""@physics.org - or as Reply-To, if any.             |

[toc] | [prev] | [next] | [standalone]

#38105

On Monday, 20 January 2020 00:39:53 UTC+1, dr.j.r...@gmail.com  wrote:
> On Sunday, 19 January 2020 18:07:34 UTC, Julio Di Egidio  wrote:
> 
> > LOL.  Haven't you and the others noticed that you are replying to a thread
> > from 1998?
> 
> One does not reply to a thread; one replies to an article.  My first article
> in the thread was only technically a Reply; in essence, it proposed renewing
> the question.

Besides that it's not an article but just a technical question, I hadn't
even mentioned it but it is actually VERY inappropriate to resurrect years
old threads, you guys still can't get your head around the fact that this
is not a forum and you are rather messing up with the Usenet ARCHIVE.

I mean, I am even being charitable, you guys have no fucking clue...

HTH and EOD.

Julio

[toc] | [prev] | [standalone]

Back to top | Article view | comp.lang.javascript

csiph-web