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variable / @typed/fx

Fx.dropUntil

Drops elements from an Fx until a predicate returns true. Emits from the first element for which the predicate returns true (including that element) and all following elements.

Package version
2.0.0-beta.13
Category
Selecting values
Since
1.0.0
Member of
Fx

Follow one execution

Drops elements from an Fx until a predicate returns true. Emits from the first element for which the predicate returns true (including that element) and all following elements.

Fx timelinedropUntil(isConnected)dropUntil
OperatordropUntil(isConnected)
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 gate is local to one run and discarded on completion or interruption. No resources are acquired and the source’s errors and services pass through unchanged.

Source implementation · Learn the surrounding model

Compare all Fx timelines →

Import

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

Access Fx.dropUntil through the imported Fx export. Its declaration below describes the member.

This public exposure is a re-export. Its import path is supported; declaration documentation is shared with the other public exposures below.

Signatures

export declare const dropUntil: {
    <A>(predicate: (a: A) => boolean): <E, R>(fx: Fx<A, E, R>) => Fx<A, E, R>;
    <A, E, R>(fx: Fx<A, E, R>, predicate: (a: A) => boolean): Fx<A, E, R>;
};

Why

dropUntil opens a one-way gate at the first matching value. The match and every later value emit once in source order; after opening, the predicate is no longer consulted.

Ownership and lifetime

The gate is local to one run and discarded on completion or interruption. No resources are acquired and the source’s errors and services pass through unchanged.

Examples

import { Fx } from "@typed/fx"

const ready = Fx.fromIterable([1, 2, 3]).pipe(Fx.dropUntil((n) => n >= 2))

Other public imports

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

Source