In Skyrim Multiplayer there are no dedicated clientside scripts. Code snippets that runs client-side are passed as strings to makeProperty, updateOwner and updateNeighbor which are described in Serverside Scripting Reference.
In updateOwner / updateNeighbor is equal to the value of a property that is processed currently or undefined if there is no value or it's not visible due to flags.
ctx.state
A writable object that is used to store data between updateOwner/updateNeighbor calls or makeProperty initializations.
state is currently shared between properties.
ctx.get()
Get the value of the specified property. Built-in properties are not supported properly, so attempts getting them are leading to the undefined behavior.
ctx.getFormIdInServerFormat()
Gets serverside formId by clientside formId or 0 if not found.
ctx.getFormIdInClientFormat()
Opposite to getFormIdInServerFormat. Gets clientside formId by serverside formId or 0 if not found.
ctx.respawn()
Respawns ctx.refr immediately.
ctx.sendEvent()
Available only in makeProperty context. Sends an event to the server.