Map reduce failed with special character (utf-8) and a pipe ( | )

Hi,

I just want to use the map reduce function of MongoDB. So I wrote a simple map_index function in javascript :

function map_index()
{
var _translit = [
[/ä|æ/g, 'ae'],
];
...
...
...

After that, I try to load the file (index.js) into Mongo Shell and :

> load('index.js');
map reduce failed: {
"assertion" : "map compile failed: JS Error: SyntaxError: unterminated regular expression literal nofile_b:1",
"assertionCode" : 9012,
"errmsg" : "db assertion failure",
"ok" : 0
}

There is no problem if I remove "| æ".

var _translit = [
[/ä/g, 'ae'],
];

The same behavior when I remove "ä" and keep "æ".

Of course, the file is encoded in utf-8. Full test code can be found as Attachment.