1: Right now, the page does not pass the 'what is it?' test at a meaningful level. I mean I know I'm looking at some JavaScript and something that looks like it's output, but after reading your comment that's not the important bit.

2: For feedback purposes, I think providing instruction/explanation on the page would be a big improvement. That could be as simple as the explanation you just provided. The implementation could be as minimal as commenting the code or more elaborately an HTML "header".

3: As a tool shared with other people, 'What it is' is the first thing people need to know. So a "product" landing page (could be as simple as text) is probably appropriate. to move instructions out of the implementation. A more elaborate version might have a hyperlink to a code repository...'how to get it' is probably the second piece of infrastructure for a "product".

4: Using Firefox, "back" was broken.

5: It's not clear what javascript functionality is available and what is not. I could create DOM elements but not add them to the output. That's the sort of documentation that a 'product' needs.

Good luck.