Hello,
I'm a Czech freelancer living in Sweden, so in both countries we work a lot with special characters. More exactly German and Swedish has almost same character set, so I can definitely help.
But before that:
1. Unfortunately we cannot create a global charset option - so what is your default character set on the site?
If you work with UTF-8, there is no problem for german, no matter which kind of utf-8 you use for DB, so there is NO need to be scared from chars like öäå.
If you have already all texts using the entities like & # 228;, you have to manually decode them prior using the string in javascript. If you use it in HTML, you can simply use innerHTML = "Vielen Dank für Ihre Anfrage. Wir bemühen uns, innerhalb von 2 Arbeitstagen zu antworten." it will be solved/decoded automatically and you can then take it back for alert. If you have possibility to process the text in PHP before using in Javascript, use simply htmlentity_decode() on the error message. It works well with different encodings. If you cannot use PHP and cannot put the string into innerHTML, then you have to create javascript based method for it, something like: [login to view URL]
That's about it:) Let me know if it helps or if you need more info.
Regards,
Luk