[whatwg] Character encoding of document.open()ed documents

And Clover and-py at doxdesk.com
Wed Mar 31 20:26:32 PDT 2010

Henri Sivonen wrote:

> Spec change request: Please change the spec to say that document.open()
> sets the document's character encoding to UTF-8

+1. UTF-16 is a troublesome encoding for [X]HTML[5] documents and should 
be consistently discouraged; as a ASCII-non-superset it interacts very 
poorly with byte interfaces in HTTP and form submissions.

No browser will actually try to submit a form as UTF-16 for this reason, 
but it still causes problems. eg. Firefox misleadingly sets the 
`_charset_` hack field to 'UTF-16' even though the submission is 

> even though the parser operates on UTF-16 DOMStrings.

The term 'UTF-16' can mean two very different things: either a sequence 
of 16-bit code units (as in DOMString), or a sequence of bytes which, 
taken as UTF-16LE or UTF-16BE, represent 16-code units. Unicode's 
tradition of conflating the meanings of the code unit sequence and the 
byte sequence has caused much confusion.

DOM Level 3 LS made the mistake of saying that because DOMStrings are 
UTF-16-code-units, XML documents parsed from 
`LSInput.characterStream`/`StringData` should receive the `encoding` 
'UTF-16', as if the parser has done a conversion from UTF-16-bytes to 
characters, though no such process has actually taken place. 
Consequently when you serialise a document parsed from a string in DOM 
Level 3 LS you get an unexpected and unwanted UTF-16 document.

And Clover
mailto:and at doxdesk.com

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