The proxy allows interaction with properties as if they were common JavaScript objects. In general every property that can be mapped in a reasonable manner to a native JavaScript object is mapped in that way. For example, interaction with a proxied ArrayProperty feels like working with an JavaScript array. All functions and access patters that can be used on a JavaScript array are available.
Any modification is directly applied to the data in PropertyDDS without caching data locally and data is loaded lazily on access.