Wel it's easy enough to transliterate every breakspace into space, and that would fix this problem, but would it break something else?

alert("hello world");

That works now, but if I replaced breakspace mindlessly the string would change.
And probably breakspace could be part of a regexp.
I don't know, but other browsers manage it,
some using the same js engine we are using, so they must do something.

I see in that nasa js lots of other utf8 symbols in strings, just not breakspace, as it happens.

Kevin this is good detective work.

any thoughts on replacing breakspace with space, or other ideas?

You notice I remove the leading byte order mark, if any, at the start of javascript, jseng-moz.cpp line 2465.
I must have run into that one before.

Karl Dahlke