API reference > @kontsedal/olas-core > defineController

defineController() function

Create a controller definition. The factory is stored on the returned object and invoked during createRoot / ctx.child to build instances.

Props defaults to void so a factory written as (ctx) => ... is typed as ControllerDef<void, Api> — the form createRoot requires.

Signature:

export declare function defineController<Props = void, Api = unknown>(factory: (ctx: Ctx, props: Props) => Api, options?: DefineControllerOptions): ControllerDef<Props, Api>;

Parameters

Parameter	Type	Description
factory	(ctx: Ctx, props: Props) => Api
options	DefineControllerOptions	(Optional)

Returns:

ControllerDef<Props, Api>

Example

export const counter = defineController(
  (ctx) => {
    const count = signal(0)
    return { count, increment: () => count.update((n) => n + 1) }
  },
  { name: 'counter' },
)