User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.2) Gecko/20060308 Firefox/1.5.0.2 Build Identifier: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.0.2) Gecko/20060308 Firefox/1.5.0.2 The current E4X spec makes it hard to process XML files. Reading the whole document including the '<?xml version="1.0"?>' Processing Instruction results in an Error. See https://bugzilla.mozilla.org/show_bug.cgi?id=290525 To use E4X with Mozilla (especially for extensions or XULRunner based applications) the Mozilla implementation should accept that processing instruction if it's the first text in the string. This bug was filled regarding https://bugzilla.mozilla.org/show_bug.cgi?id=290525#c5 Reproducible: Always

And of course the original processing instruction should be returned from ToString.

Marking as new; this is something brendan is passionate about.

E4X will be removed again from Spidermonkey (bug 788293)