The media type text/xml must be supported

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
return doc.documentElement.localName == "y";

The media type application/xml must be supported

var doc = new DOMParser().parseFromString("<y/>", "application/xml");
return doc.documentElement.localName == "y";

DOMParser with error handler must be supported

var handler = function(err) { return false; }
var parser = new DOMParser(handler);
return !!parser;

DOMParser error handler must be called on fatal errors

var called = false;
var handler = function(err) { called = true; return false; }
var parser = new DOMParser(handler);
parser.parseFromString("<y", "application/xml");
return called;

Internet media types are case-insensitive by definition

var doc = new DOMParser().parseFromString("<y/>", "tExt/xMl");
return doc.documentElement.localName == "y";

White space surrounding the media type must be ignored

var doc = new DOMParser().parseFromString("<y/>", " text/xml ");
return doc.documentElement.localName == "y";

Throw on syntax errors in the media type

try {
  var doc = new DOMParser().parseFromString("<y/>", "xml");
  return false;
} catch(e) {
  return true;
}

Throw on syntax errors in the media type

try {
  var doc = new DOMParser().parseFromString("<y/>", "");
  return false;
} catch(e) {
  return true;
}

Throw on media types that cannot be XML

try {
  var doc = new DOMParser().parseFromString("<y/>", "image/png");
  return false;
} catch(e) {
  return true;
}

The media type does not have a default value

try {
  var doc = new DOMParser().parseFromString("<y/>");
  return false;
} catch(e) {
  return true;
}

Encoding declarations must be ignored

var s = "<?xml version='1.0' encoding='iso-8859-1'?><y>\uF6F6</y>";
var doc = new DOMParser().parseFromString(s, "text/xml");
return doc.documentElement.textContent.indexOf("\uF6F6") >= 0;

inputEncoding must be null after parsing

var s = "<?xml version='1.0' encoding='iso-8859-1'?><y>\uF6F6</y>";
var doc = new DOMParser().parseFromString(s, "text/xml");
return !doc.inputEncoding;

xmlEncoding must have a value equivalent to the encoding declaration

var s = "<?xml version='1.0' encoding='windows-1252'?><y>\uF6F6</y>";
var doc = new DOMParser().parseFromString(s, "text/xml");
/* It might be acceptable to use an alias so this a bit fuzzy */
return !doc.xmlEncoding || doc.xmlEncoding.toLowerCase() == 'windows-1252';

Unicode signatures are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "\uFEFF<?xml version='1.0'?><y/>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Unicode signatures are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "\uFEFF\uFEFF<?xml version='1.0'?><y/>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Unicode signatures are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "\uFEFF<y/>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Unicode signatures are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "\uFEFF\uFEFF<y/>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Unicode signatures are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "\uBBEF\u3CBF\u7979\u3E2F";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Unicode signatures are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "\uEFBB\uBF3C\u7979\u2F3E";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Incomplete documents are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "<y>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Incomplete documents are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "<y/><!--";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Not well-formed due to bad character reference

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "<y>&#xFF000000F6;</y>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Not well-formed due to bad character reference

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "<y>&#18446744073709551862;</y>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Unpaired surrogates are not allowed

var handler = function(err){ return false; };
var parser = new DOMParser();
try { parser = new DOMParser(handler); } catch (e) {}
var s = "<y>\uD800</y>";
try {
  var doc = parser.parseFromString(s, "text/xml");
  return doc.documentElement.localName == "parsererror";
} catch(e) {
  return true;
}

Unserializable content, "--" in comment

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var cmt = doc.createComment("--");
  var str = new XMLSerializer().serializeToString(cmt);
  return false;
} catch (e) {
  return true;
}

Unserializable content, PI with 'xml' as target

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var pi = doc.createProcessingInstruction("xml", 'version="1.0"');
  var str = new XMLSerializer().serializeToString(pi);
  return false;
} catch (e) {
  return true;
}

Unserializable content, PI with '?>' as data

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var pi = doc.createProcessingInstruction("example", '?>');
  var str = new XMLSerializer().serializeToString(pi);
  return false;
} catch (e) {
  return true;
}

Unserializable content, document without document element

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  doc.removeChild(doc.documentElement);
  var str = new XMLSerializer().serializeToString(doc);
  return false;
} catch (e) {
  return true;
}

Unserializable content, xmlns element

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var sub = doc.createElementNS("http://www.w3.org/2000/xmlns/", "y");
  var str = new XMLSerializer().serializeToString(sub);
  return false;
} catch (e) {
  return true;
}

Unserializable content, unpaired surrogate in text

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var txt = doc.createTextNode("\uD800");
  var str = new XMLSerializer().serializeToString(txt);
  return false;
} catch (e) {
  return true;
}

Unserializable content, unpaired surrogate in text via splitText

try {
  /* TODO: need to review this */
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var txt = doc.createTextNode("\uD800\uDC00");
  doc.documentElement.appendChild(txt);
  var sub = txt.splitText(1);
  doc.documentElement.removeChild(sub);
  var str = new XMLSerializer().serializeToString(doc);
  return false;
} catch (e) {
  return true;
}

Goldfarb's First Law of Text Processing -- attribute white space

var doc = new DOMParser().parseFromString("<y y='&#xa;'/>", "text/xml");
var str = new XMLSerializer().serializeToString(doc);
return str.indexOf('&') >= 0;

Namespace declarations are fixed as necessary

var doc1 = new DOMParser().parseFromString("<y/>", "text/xml");
doc1.documentElement.setAttributeNS('example:', 'example', 'example');
var str = new XMLSerializer().serializeToString(doc1);
var doc2 = new DOMParser().parseFromString(str, "text/xml");
return doc2.documentElement.getAttributeNS('example:', 'example')
  == 'example';

Serialization must be explicit about elements in no namespace

var s = "<y xmlns='example:'><y xmlns=''><y/></y></y>";
var doc = new DOMParser().parseFromString(s, "text/xml");
var sub = doc.documentElement.firstChild.firstChild;
var str = new XMLSerializer().serializeToString(sub);
return str.indexOf("xmlns") >= 0;

No Unicode signature in the serialized document

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
var str = new XMLSerializer().serializeToString(doc);
return str.indexOf("\uFEFF") < 0;

No c0 control characters unless output is XML 1.1

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var txt = doc.createTextNode("\u000C");
  doc.documentElement.appendChild(txt);
  var str = new XMLSerializer().serializeToString(doc);
  return str.indexOf("1.1") >= 0;
} catch (e) {
  return true;
}

A charset parameter in the type argument must have no effect

try {
  var doc = new DOMParser().parseFromString("<y>\uF6F6</y>",
    "text/xml;charset=iso-8859-1");
  return doc.documentElement.textContent.indexOf("\u00F6") < 0;
} catch (e) {
  return true;
}

Serializing DocumentFragment nodes

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
var node = doc.createDocumentFragment();
node.appendChild(doc.createTextNode("text"));
node.appendChild(doc.createComment("comment"));
var s = new XMLSerializer().serializeToString(node);
var doc2 = new DOMParser().parseFromString("<y>" + s + "</y>", "text/xml");
return doc2.documentElement.firstChild.nodeValue == "text"
  && doc2.documentElement.firstChild.nextSibling.nodeValue == "comment";

Serializing Text nodes escapes <

var doc = new DOMParser().parseFromString("<y>&lt;</y>", "text/xml");
var sub = doc.documentElement.firstChild;
var str = new XMLSerializer().serializeToString(sub);
return str.indexOf('<') < 0;

Serializing Text nodes escapes ] ] >

var doc = new DOMParser().parseFromString("<y>]]&gt;</y>", "text/xml");
var sub = doc.documentElement.firstChild;
var str = new XMLSerializer().serializeToString(sub);
return str.indexOf('&') >= 0;

Serializing DocumentType nodes

var s = "<!DOCTYPE y><y/>"
var doc = new DOMParser().parseFromString(s, "text/xml");
var sub = doc.doctype;
var str = new XMLSerializer().serializeToString(sub);
return str.indexOf('!DOCTYPE') >= 0;

Serializing DocumentType nodes with internal subset

var s = "<!DOCTYPE y [<!ENTITY example ''>]><y/>"
var doc = new DOMParser().parseFromString(s, "text/xml");
var sub = doc.doctype;
var str = new XMLSerializer().serializeToString(sub);
return str.indexOf('!ENTITY') >= 0;

Serializing DocumentType nodes with no ownerDocument

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
var dtd;
try {
  dtd = doc.implementation.createDocumentType('html',
    "-//W3C//DTD XHTML 1.0 Strict//EN",
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd");
} catch (e) {
  return true;
}
var str = new XMLSerializer().serializeToString(dtd);
return str.indexOf("!DOCTYPE") >= 0;

Serializing ProcessingInstruction nodes

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
var pi = doc.createProcessingInstruction("example", 'test');
var str = new XMLSerializer().serializeToString(pi);
return str.indexOf('example') >= 0 && str.indexOf('test') >= 0;

Serializing CDATASection nodes

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
var cds = doc.createCDATASection('example');
var str = new XMLSerializer().serializeToString(cds);
return str.indexOf('example') >= 0 || str.indexOf('&') >= 0;

Serializing CDATASection nodes containing ] ] >

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
var cds;
try {
  cds = doc.createCDATASection(']]' + '>');
} catch (e) {
  return true;
}
var str = new XMLSerializer().serializeToString(cds);
return str.indexOf(']]') >= 0 || str.indexOf('&') >= 0;

Serializing Attr nodes only gives value for some reason

var doc = new DOMParser().parseFromString("<y k='v'/>", "text/xml");
var att = doc.documentElement.attributes[0];
var str = new XMLSerializer().serializeToString(att);
return str.indexOf('k') < 0 && str.match(/v|&/);

Serializing XPathNamespace nodes gives empty string for some reason

try {
  var doc = new DOMParser().parseFromString("<y/>", "text/xml");
  var res = doc.evaluate("//namespace::*", doc, null, 9, null);
  var str = new XMLSerializer().serializeToString(res.singleNodeValue);
  return str == "";
} catch (e) {
  return true;
}

There is no proper base URI so document.baseURI defaults to null

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
return !doc.baseURI;

There is no default document URI for documents encoded as strings

var doc = new DOMParser().parseFromString("<y/>", "text/xml");
return !doc.documentURI;

Implementations should allow exchanging nodes between documents

var doc1 = new DOMParser().parseFromString("<y/>", "text/xml");
var doc2 = new DOMParser().parseFromString("<z/>", "text/xml");
var node = doc1.importNode(doc2.documentElement, false);
doc1.documentElement.appendChild(node);
return doc1.documentElement.firstChild.localName == 'z';