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From: John-Paul Stewart <jpstewart@personalprojects.net>
Newsgroups: comp.lang.javascript
Subject: Re: ASCII unicode values
Date: Thu, 26 Nov 2020 19:02:51 -0500
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On 2020-11-26 10:35 a.m., Jonas Thörnvall wrote:
> Why does not javascript follow the OS and language implementation of
> its reflection on keypresses, why does it use some internal
> "charcode?" set where your keypresses do not follow the way you use
> them?
> 
> key = e.keyCode ? e.keyCode : e.which; 
> character= String.fromCharCode(key);
You are mixing up keyCodes and charCodes.  String.fromCharCode() expects
its parameter(s) to be charCode(s), as you should be able to see from
the name.  Those charCodes are "UTF-16 code units" according to the docs:

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/fromCharCode

But what you're passing is a keyCode instead.  That is "a system and
implementation dependent numerical code identifying the unmodified value
of the pressed key" according to its documentation:

https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/keyCode

You are clearly very confused since you are passing a system-dependent
keyCode to a function that is expecting a UTF-16 charCode.  They are not
the same thing.

You might want key = e.charCode instead.

Or, since both charCode and keyCode are deprecated and non-standard, you
should probably read up on the key property instead, as was suggested by
Michael Haufe in his post to a different thread back on 2020-11-11.

https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/key