I don't know the background of your dev...
your competitor appears to have their table already built in the HTML, and their AJAX call just gets the raw data from the server, then inserts that into the HTML table (which would be more efficient than fetching the whole HTML from the server with each AJAX request) and you could go that route if you wanted. Or, considering what you already have- the quick shortcut would be to do what I said before. It would save a little dev time now, but cost more in the long run...
Either one would accomplish your goal of having a similar calculator to your competition (because they are using AJAX for their calculator).
Allwisend bin ich nicht, doch viel ist mir bewursst