How to parse non-UTF8 XML in browsers with Javascript?

问题

I have a XML string encoded in big5:

atob('PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iYmlnNSIgPz48dGl0bGU+pKSk5TwvdGl0bGU+')

(<?xml version="1.0" encoding="big5" ?><title>中文</title> in UTF-8.)

I'd like to extract the content of <title>. How can I do that with pure Javascript in browsers? Better to have lightweight solutions without jquery or emscripten.

Have tried DOMParser:

(new DOMParser()).parseFromString(atob('PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iYmlnNSIgPz48dGl0bGU+pKSk5TwvdGl0bGU+'), 'text/xml')

But neither Chromium nor Firefox respects the encoding attribute. Is it a standard that DOMParser supports UTF-8 only?

回答1:

I suspect the issue isn't DOMParser, but atob, which can't properly decode what was originally a non-ascii string.*

You will need to use another method to get at the original bytes, such as using https://github.com/danguer/blog-examples/blob/master/js/base64-binary.js

var encoded = 'PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0iYmlnNSIgPz48dGl0bGU+pKSk5TwvdGl0bGU+';
var bytes = Base64Binary.decode(encoded);

and then some method to convert the bytes (i.e. decode the big5 data) into a Javascript string. For Firefox / Chrome, you can use TextDecoder:

var decoder = new TextDecoder('big5'); 
var decoded = decoder.decode(bytes);

And then pass to DOMParser

var dom = (new DOMParser()).parseFromString(decoded, 'text/xml');
var title = dom.children[0].textContent;

You can see this at https://plnkr.co/edit/TBspXlF2vNbNaKq8UxhW?p=preview

---

*One way of understanding why: atob doesn't take the encoding of the original string as a parameter, so while it must internally decode base64 encoded data to bytes, it has to make an assumption on what character encoding those bytes are to then give you a Javascript string of characters, which I believe is internally encoded as UTF-16.

来源：https://stackoverflow.com/questions/38292228/how-to-parse-non-utf8-xml-in-browsers-with-javascript