Conditional Discount in cart based on properties

[minus81]

So I am working on a store that is using Bold options and custom liquid properties for some pretty advanced customizations. They are looking to add a specific discount to products that are left unmodified.

So for example.

I have product A which has a cost of $100,   and it has a custom property that allows the user to change the default color ( Not variant but using the properties liquid objects ).

If the property of said product is left unmodified ( or its value is set to "no" ) then the discount code would be applied to the cart for that product, if the property is modified then the discount could obviously not be added.

Now, assuming they add (3) of this product, and (1) is left unmodified then the discount would only be added once.

I've seen some people do some FE JS work and check the cart drawer and add the discount upon cart updating by checking the cart items in the front end, but is that a proper method, or can Shopify Scripts / Functions product be a better approach?