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throttle

Limits emissions to configured leading and trailing edges of fixed windows.

Pass { duration, leading, trailing } for trailing or both-edge behavior. A duration alone defaults to { leading: true, trailing: false }.

Package version
2.0.0-beta.7
Category
Time and rate
Since
1.0.0

Follow one execution

Limits emissions to configured leading and trailing edges of fixed windows. Pass { duration, leading, trailing } for trailing or both-edge behavior. A duration alone defaults to { leading: true, trailing: false }.

Fx timelinethrottle keeps leading and trailing values in a 100ms window (50ms slots)throttle
Operatorthrottle({ duration: 100ms, leading: true, trailing: true })
Read this diagram

Follow each lane from left to right. Events stacked vertically share a tick; the green cursor marks the current time across every lane.

  • A value
    The text inside the pill is the emitted value.
  • Work starts
    The raised chevron starts an inner run (^ in the source).
  • The run returns
    The vertical bar ends this lane’s run.
  • A cause is delivered
    The exclamation mark belongs to this lane.
  • Work is interrupted
    The cross marks cancellation of this run.
  • Current time
    The line and diamond move together across all lanes.
  • Happening now
    A highlighted event is at the current tick.
  • Still ahead
    Muted, dashed values have not happened yet.
  • Time continues
    The lane’s arrow is not a return marker. An empty stretch can be quiet work that is still running.

Illustrated ticks start at 0. At 1×, one illustrated tick takes one second; captions specify real durations when timing matters. A cause or interruption belongs to its lane, and other work may continue. Scroll horizontally to inspect the rest of a long timeline.

The first value opens a window. Leading mode emits it immediately. Values arriving while open replace one pending latest value; trailing mode emits that value when the timer closes, except that both-edge mode does not repeat the first value unless another arrived. Windows never overlap. Source errors propagate, source completion waits for the active window, and interruption stops the scoped timer and discards pending state.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

import { throttle } from "@typed/fx/Fx";

Signatures

export declare const throttle: {
    (duration: Duration.Input): <A, E, R>(fx: Fx<A, E, R>) => Fx<A, E, R | Scope.Scope>;
    (options: ThrottleOptions): <A, E, R>(fx: Fx<A, E, R>) => Fx<A, E, R | Scope.Scope>;
    <A, E, R>(fx: Fx<A, E, R>, duration: Duration.Input): Fx<A, E, R | Scope.Scope>;
    <A, E, R>(fx: Fx<A, E, R>, options: ThrottleOptions): Fx<A, E, R | Scope.Scope>;
};

Why

Throttling bounds push frequency while allowing immediate feedback, a final settled value, or both, without moving timing state outside the Fx graph.

Ownership and lifetime

The first value opens a window. Leading mode emits it immediately. Values arriving while open replace one pending latest value; trailing mode emits that value when the timer closes, except that both-edge mode does not repeat the first value unless another arrived. Windows never overlap. Source errors propagate, source completion waits for the active window, and interruption stops the scoped timer and discards pending state.

Examples

import { throttle } from "@typed/fx/Fx"
import { fromIterable } from "@typed/fx/Fx"

const bounded = throttle(fromIterable([1, 2, 3]), {
  duration: "250 millis",
  leading: true,
  trailing: true
})

Other public imports

These import paths expose the same declaration. Each page retains its own public name and signature.

Source