throttling

The throttling() function prevents multiple runs of the same flow from happening too close together. It can either return a fallback value immediately or keep only the last skipped call with keepLast: true.

Interactive example

Syntax

function throttling<
	GenericValue extends unknown = undefined,
	GenericKeepLast extends boolean = false
>(
	time: number,
	params?: {
		returnValue?: GenericValue;
		keepLast?: GenericKeepLast;
	}
): Generator | AsyncGenerator

Parameters

• time: Minimum time window between two runs of the same flow.
• params.returnValue: Value returned when a run is skipped during the throttling window.
• params.keepLast: When set to true, only the last skipped call is replayed after the wait.

Return value

By default, throttling() returns a synchronous generator. With keepLast: true, it returns an async generator that waits before resuming the last preserved call.

Notes

• Internal state is stored in a WeakMap keyed by the executed flow reference.
• To share the same throttling window across calls, reuse the same flow created with F.create(...) or the same function returned by F.toFunction(...).
• An inline F.run(function *() { ... }) does not share that window with later calls.
• If the same execution yields throttling(...) multiple times, only the first encountered effect is applied by the runner.

See also

• queue - Serializes runs instead of skipping them
• debounce - Waits before letting only the latest run continue
• calledByNext - Triggers a callback when a later run replaces the current one
• run - Executes the flow and applies throttling effects