JSFiddle - React, Tailwind, and code Playground
JavaScript
var myXml = "<one attr='a'><two attr='b'/><three attr='c'><four attr='d'/></three></one>";
myXml = $.parseXML(myXml);
$(myXml).find('two').attr('attr','new value'); //<-- This works
$(myXml).find('three').append($('<five>some value</five>')); //<-- Does not work
alert($(myXml).find('five').text()) // <--Null