Retrieve SVG Dom in object element as text

I try to figure out how to retrieve the whole svg-dom as text in a variable via Javascript.

I have no problems to reference the embedded svg file. But innerHTML or outerHTML on the SVG Element will not work and I hope that I don't have to loop through all child nodes and every single attribute.

Reason for my question:

I would like to offer the visitors of my page and my students the svg code which is dynamically modified by user actions.

You may take a look at the example of Pythagoras on my site: SVG sample with Pythagoras triangle

Thanks in advance for you help! It's my first question on this site.