If it is new to the DOM it will get added. If it is present in the DOM (based on id and other attributes when the id is not present) it will not get recreated.

If it is new to the DOM it will get added. If it is present in the DOM (based on id and other attributes when the id is not present) it will not get recreated. It may be left alone or it may have its attributes merged. There are a ton of edge cases though, which is why there is no native DOM diffing yet.