I convert a string of HTML into an object so I can manipulate like this

var HTMLStr = "<div><span>TESTING</span></div><h1>HEADING</h1>";
var HTMLDom = $(HTMLStr).find("h1").remove();
var newHTMLStr = ???

Question: How can I convert the HTMLDom back into a string after manipulation?

I have tried the following: http://stackoverflow.com/a/652771/3758078 But that only converts the first element found, and not the rest.