Save/Reload User-Defined Components

I would like to see user-defined components that are dynamically added to blocks, items, and entities via javascript be saved and reloaded with the world.  To make it more flexible, perhaps when a custom component is registered it could be designated as "persistent" (saved/loaded with the world) or "non-persistent" (temporary, disappearing when game is turned off).

Currently, the inability to save/reload custom component data along with the lack of any other sort of persistent custom storage limits the types of add-ons that can be developed.

I am sure there are many other use cases, but a specific use case I have in mind is a teleportation add-on where a "waypoint" item could be created for a specific set of world coordinates (which I would save in a custom component), and then be used with a teleporter to instantly teleport the player to the coordinates of the waypoint.  If waypoint coordinates are lost every time the game is topped, it really limits the usefulness of this type of add-on.

Thank you.