Systems and methods are described for passing a data item to and obtaining the data item from a scripting environment hosted by a host environment, wherein each environment uses a different representation of the data item. The host environment passes the data item to the scripting environment by passing a host environment representation of the data item that is hidden from developers of scripts to be executed by the scripting environment. This enables the original host environment representation of the data item to be preserved even after the data item has been passed to and from the scripting environment in the case where the scripting environment does not modify the data item, and also facilitates lazy conversion of the data item or avoidance of conversion entirely in the case where the scripting environment does not modify the data item.