Converts a sequence of ANSI characters to UTF-8 and vice-versa.

[UPDATED CODE AND HELP CAN BE FOUND HERE]

//+ Jonas Raoni Soares Silva
//@ http://jsfromhell.com/geral/utf-8 [v1.0]

UTF8 = {
	encode: function(s){
		for(var c, i = -1, l = (s = s.split("")).length, o = String.fromCharCode; ++i < l;
			s[i] = (c = s[i].charCodeAt(0)) >= 127 ? o(0xc0 | (c >>> 6)) + o(0x80 | (c & 0x3f)) : s[i]
		);
		return s.join("");
	},
	decode: function(s){
		for(var a, b, i = -1, l = (s = s.split("")).length, o = String.fromCharCode, c = "charCodeAt"; ++i < l;
			((a = s[i][c](0)) & 0x80) &&
			(s[i] = (a & 0xfc) == 0xc0 && ((b = s[i + 1][c](0)) & 0xc0) == 0x80 ?
			o(((a & 0x03) << 6) + (b & 0x3f)) : o(128), s[++i] = "")
		);
		return s.join("");
	}
};

Example

var s = "aáéíóúe";
document.write(
	('UTF8.encode("' + s + '") = ').bold(), UTF8.encode(s), "<br />",
	('UTF8.decode(UTF8.encode("' + s + '"))) = ').bold(), UTF8.decode(UTF8.encode(s))
);

I was having problems with my ajax lookups when the database fields returned weird characters like the copyright symbol. The responseXML would be blank. After many searches I found you need to output in utf-8 and add an xml declaration to the output that says it is utf-8. Here is the code below in vb.net for asp.net v1.1

   Private Sub OutputDataSetAsXML(ByRef dsSource As System.Data.DataSet)

      Dim xmlDoc As System.Xml.XmlDataDocument
      Dim xmlDec As System.Xml.XmlDeclaration
      Dim xmlWriter As System.Xml.XmlWriter

      ' setup response
      Me.Response.Clear()
      Me.Response.ContentType = "text/xml"
      Me.Response.Charset = "utf-8"
      xmlWriter = New System.Xml.XmlTextWriter(Me.Response.OutputStream, System.Text.Encoding.UTF8)

      ' create xml data document with xml declaration
      xmlDoc = New System.Xml.XmlDataDocument(dsSource)
      xmlDoc.DataSet.EnforceConstraints = False
      xmlDec = xmlDoc.CreateXmlDeclaration("1.0", "UTF-8", Nothing)
      xmlDoc.PrependChild(xmlDec)

      ' write xml document to response
      xmlDoc.WriteTo(xmlWriter)
      xmlWriter.Flush()
      xmlWriter.Close()
      Response.End()

   End Sub