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InitialState

InitialState<Context, Protocol>(TargetState): void

Declares TargetState as the initial substate of its direct parent composite.

Apply as a TypeScript decorator or call as a function at class definition time. Exactly one initial child is allowed per parent; a second mark throws InitialStateError.

Type Parameters​

Context​

Context

Domain context type

Protocol​

Protocol extends { } | undefined

Vocabulary interface

Parameters​

TargetState​

StateClass<Context, Protocol>

Child state class whose parent is Object.getPrototypeOf(TargetState.prototype).constructor

Returns​

void

Throws​

InitialStateError when the parent already has an initial substate

Remarks​

During makeHsm initialization, the runtime descends @InitialState chains from the root until the deepest initial leaf is active, running StateEvents.onEntry along the path.

Example​

class Composite extends TopState {}

@InitialState
class Idle extends Composite {}