Prevent entry of text in foreign characters

[lausianne]

Hello,

Usually we are concerned about enabling use of various languages with Joomla. Now I had, for the first time, a request from a client to disable the use of foreign languages on his site. The problem is that someone placed an order in his Virtuemart shop and wrote everything in Chinese.
The client now asks me to limit the characters to be used in form fields to latin characters.

Do you have an idea how to achieve that with reasonable effort?

My first idea is to write something up in Javascript, to check text in form fields for characters outside a set of characters (RegEx). Maybe this or something similar/better already exists?

Thank you!


EDIT: googled further and came across this, seems simple enough:
https://www.w3schools.com/tags/att_form ... harset.asp
EDIT: Added this in RSForm, makes no difference -> fail

[SharkyKZ]

Regex is fine. If Form API is used for the form, create a form rule. See core form rules for example https://github.com/joomla/joomla-cms/tr ... /Form/Rule.

[infograf768]

Not sure using only accept-charset="ISO-8859-1" will work.
As Joomla is using utf8, ISO-8859-1 may not display correctly for accented or other special letters like ç.
One may have to reconvert these to utf8 by using `utf8_encode`