Get the string representation of a DOM node

What you're looking for is 'outerHTML', but wee need a fallback coz it's not compatible with old browsers.

var getString = (function() {
  var DIV = document.createElement("div");

  if ('outerHTML' in DIV)
    return function(node) {
      return node.outerHTML;
    };

  return function(node) {
    var div = DIV.cloneNode();
    div.appendChild(node.cloneNode(true));
    return div.innerHTML;
  };

})();

// getString(el) == "<p>Test</p>"

You'll find my jQuery plugin here: Get selected element's outer HTML

Under FF you can use the XMLSerializer object to serialize XML into a string. IE gives you an xml property of a node. So you can do the following:

function xml2string(node) {
   if (typeof(XMLSerializer) !== 'undefined') {
      var serializer = new XMLSerializer();
      return serializer.serializeToString(node);
   } else if (node.xml) {
      return node.xml;
   }
}

I dont think you need any complicated script for this. Just use

get_string=(el)=>el.outerHTML;

You can create a temporary parent node, and get the innerHTML content of it:

var el = document.createElement("p");
el.appendChild(document.createTextNode("Test"));

var tmp = document.createElement("div");
tmp.appendChild(el);
console.log(tmp.innerHTML); // <p>Test</p>

EDIT: Please see answer below about outerHTML. el.outerHTML should be all that is needed.