Computation Service API

createComputationService()

Create a service that encapsulates logic to compute a value in response to dependency changes.

It utilizes EffectProcessor under the hood.

function createComputationService<TComputed extends Record<string, unknown>>(
  effectProcessor: EffectProcessor,
): ComputationService<TComputed>

Type Parameters:

Parameter	Constraint	Default	Description
TComputed	Record<string, unknown>	-	The type of the object containing computed values.

Parameters:

Parameter	Type	Required	Description
effectProcessor	EffectProcessor	Yes	The processor that manages, tracks, and triggers effects.

Returns: ComputationService<TComputed>

interface ComputationService<TComputed extends Record<string, unknown>> {
  computed: ComputedValues<TComputed>;
  compute: ComputeFn<TComputed>;
}

Parameter	Constraint	Default	Description
TComputed	Record<string, unknown>	-	The type of the object containing computed values.

service.computed

• Type: ComputedValues<TComputed>

A collection of computed values (results from the compute method).

type ComputedValues<TComputed extends Record<string, unknown>>
  = Partial<{ [K in keyof TComputed]: TComputed[K] }>

service.compute()

• Type: ComputeFn<TComputed>

Compute a value in response to dependency changes.

The computation in this context is a side effect that derives a value (typically) from the given dependencies and keeps track of the result. The computation result can be referred to as the computed value and is available in the computed property.
The computation will only re-run when triggered and at least one of its dependencies changes.

This method calls the trackEffect method of the processor.

type ComputeFn<TComputed extends Record<string, unknown>> = <K extends keyof TComputed>(
  name: K,
  computation: () => TComputed<K>,
  depsFn: () => ComputedDeps,
  options?: ComputeOptions,
) => ComputeReturn<TComputed<K>>;

Parameter	Type	Required	Description
name	K	Yes	A unique name for the computed value, which is used as a key in the computed property.
computation	() => TComputed<K>	Yes	The function that performs the computation. The return value is the computation result.
depsFn	() => ComputedDeps	Yes	The function that resolves the dependency values of the computation.
options	ComputeOptions	No	Options to configure the computation's execution behavior.

Returns: ComputeReturn<TComputed<K>>
An object containing the computation result and a function to toggle the active state of the computation.

interface ComputeReturn<TComputed> {
  computed?: TComputed;
  toggleActive: () => void;
}

Parameter	Constraint	Default	Description
TComputed	-	-	The type of the computation result (computed value).

Property	Type	Description
computed	TComputed|undefined	The computation result.
toggleActive	() => void	The function to toggle the active state of the computation.

ComputeOptions

interface ComputeOptions {
  sync?: boolean;
}

Property	Type	Description
sync	boolean	Whether to run the computation synchronously. Default: false

ComputedDeps

Represents a dependency array of a computation that hints that it should have at least one element.

type ComputedDeps = unknown[] & { 0: unknown }