How do you use getElementById in javascript with ids that get appended by a perch identifier?
E.g in "shop's" cart the product quantity input field gets appended with a unique identifier (number) for the product .
For processing purposes, the units of qty are CM (Centimetres) but I need to show the qty to the user in M (metres), so I need to apply a conversion to the value of this input (which will be hidden) and display the result in another input (qty_m - which will need to be paired with qty by sharing that same identifier). To do the conversion I was hoping to get the value of qty by using getElementById however the ID isn't qty it actually be qty:# (unique to each cart item)