conversion of #xml with attributes to #json with attributes

how can you convert #xml with attributes to #json with attributes

these three xml converters give three different answers

• http://codebeautify.org/xmltojson
• http://www.freeformatter.com/xml-to-json-converter.html
• http://www.utilities-online.info/xmltojson/

and represent XML attributes as either

• _attr
• @attr
• -attr