解码ISO字符

I got Chinese characters encoded in ISO-8859-1, for example 兼 = 兼
Those characters are taken form the database using AJAX and sent by Json using json_encode.
I then use the template Handlebars to set the data on the page.
When I look at the ajax page the characters are displayed correctly, the source is still encoded.
But the final result displays the encrypted characters.

I tried to decode on the javascript part with unescape but there is no foreach with the template that gives me the possibility to decode the specific variable, so it crashes.
I tried to decode on the PHP side with htmlspecialchars_decode but without success.

Both pages are encoded in ISO-8859-1, but I can change them in UTF8 if necessary, but the data in the database remains encoded in ISO-8859-1.

Thank you for your help.

Are you including your text with the "double-stache" Handlebars syntax?

{{your expression}}

As the Handlebars documentation mentions, that syntax HTML-escapes its output, which would cause the results you're mentioning, where you're seeing the entity 兼 instead of 兼.

Using three braces instead ("triple-stache") won't escape the output and will let the browser correctly interpet those numeric entities:

{{{your expression}}}

You're simply representing your characters in HTML entities. If you want them as "actual characters", you'll need to use an encoding that can represent those characters, ISO-8859 won't do. htmlspecialchars_decode doesn't work because it only decodes a handful of characters that are special in HTML and leaves other characters alone. You'll need html_entity_decode to decode all entities, and you'll need to provide it with a character set to decode to which can handle Chinese characters, UTF-8 being the obvious best choice:

$str = html_entity_decode($str, ENT_COMPAT, 'UTF-8');

You'll then need to make sure the browser knows that you're sending it UTF-8. If you want to store the text in the database in UTF-8 as well (which you really should), best follow the guide How to handle UTF-8 in a web app which explains all the pitfalls.