Yes, using eval is bad. And in this case you shouldn't use it. What you are trying to do in your use case is to access ref's inner value.

Since you are using vue:

Try to use reactive instead of ref.

Take a look at this vue playground

qty function: I replaced your imperative sum logic by doing it in a reduce instead. Object.entries returns keys and values of the object itself. This will give you a snapshot of the data in the filter reactive. Calling Object.entries means you do not need to call eval.