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From: Thomas 'PointedEars' Lahn <PointedEars@web.de>
Newsgroups: comp.lang.javascript
Subject: Re: Base64 encode using using windows-1250 encoding
Date: Sat, 09 Jun 2018 09:53:48 +0200
Organization: PointedEars Software (PES)
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Thomas 'PointedEars' Lahn wrote:

> Jupi wrote:
>> Thomas 'PointedEars' Lahn expressed precisely :
>>> Jupi wrote:
>>>> I need to encode string using Central European Windows-1250 encoding.
>>> Why?
>> 
>> Because I need it.
> 
> No, you just *think* you need it.
> 
> <http://xyproblem.info/>
> 
>> […]
>> I just need to encode some string which
>> contains Easteuropean characters to base64 string.
> 
>   var b64 = window.btoa("Perišić");

This throws

| Uncaught DOMException: Failed to execute 'btoa' on 'Window': The string to 
| be encoded contains characters outside of the Latin1 range.
|     at <anonymous>:1:8

in Chromium "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like 
Gecko) Chrome/57.0.2987.98 Safari/537.36".  So apparently there is no easy 
way.

Since ECMAScript implementations only use a Unicode-compatible 16-bit 
character encoding internally, a possibility appears to be convert the 
original string to a representation of UTF-8 first, encode the individual 
UTF-8 code units as if each of them were an ISO-8859-1 code unit, and then 
encode the resulting character string with Base64.  For that, we could use 

  var b64 = window.btoa(
    encodeURIComponent("Perišić").replace(
      /%([0-9A-F]{2})|./g,
      (m, code) => (code) ? String.fromCharCode(parseInt(code, 16)) : m)
  );

Still, the question remains: Why does Base64 have to be used in the first 
place?

-- 
PointedEars
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