Hi @steftriant,
yes you can do it e.g. on the tasklist page. When you have some for example console.log statements in your code, you can see this output in the console of the browser.
Yes, I mean the problem must be the quantity value. If you delete x.Quantity from your calculation, you see the value of x.Price. I think, you can get it working after reworking the select-items.html.
Cheers
kristin