import { is, type Unit } from "effector";

Namespace for unit validators.

Methods

is.store(value)

Checks if given value is store

Returns

boolean — Type-guard

Examples

import { is, createStore, createEvent, createEffect, createDomain } from "effector";

const $store = createStore(null);
const event = createEvent();
const fx = createEffect();

is.store($store);
// => true

is.store(event);
// => false

is.store(fx);
// => false

is.store(createDomain());
// => false

is.store(fx.pending);
// => true

is.store(fx.done);
// => false

is.store($store.updates);
// => false

is.store(null);
// => false

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is.event(value)

Checks if given value is event

Returns

boolean — Type-guard

Examples

import { is, createStore, createEvent, createEffect, createDomain } from "effector";

const $store = createStore(null);
const event = createEvent();
const fx = createEffect();

is.event($store);
// => false

is.event(event);
// => true

is.event(fx);
// => false

is.event(createDomain());
// => false

is.event(fx.pending);
// => false

is.event(fx.done);
// => true

is.event($store.updates);
// => true

is.event(null);
// => false

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is.effect(value)

Checks if given value is effect

Returns

boolean — Type-guard

Examples

import { is, createStore, createEvent, createEffect, createDomain } from "effector";

const $store = createStore(null);
const event = createEvent();
const fx = createEffect();

is.effect($store);
// => false

is.effect(event);
// => false

is.effect(fx);
// => true

is.effect(createDomain());
// => false

is.effect(null);
// => false

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is.targetable

Checks if given value can be used in operators target (or be called as a function in case of events)

Returns

boolean — Type-guard

Examples

import { is, createStore, createEvent, createEffect } from "effector";

const $store = createStore(null);
const $mapped = $store.map((x) => x);
const event = createEvent();
const mappedEvent = event.map((x) => x);
const fx = createEffect();

is.targetable($store);
// => true

is.targetable($mapped);
// => false

is.targetable(event);
// => true

is.targetable(mappedEvent);
// => false

is.targetable(fx);
// => true

is.domain(value)

Checks if given value is domain

Returns

boolean — Type-guard

Examples

import { is, createStore, createEvent, createEffect, createDomain } from "effector";

const $store = createStore(null);
const event = createEvent();
const fx = createEffect();

is.domain($store);
// => false

is.domain(event);
// => false

is.domain(fx);
// => false

is.domain(createDomain());
// => true

is.domain(null);
// => false

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is.scope(value)

Checks if given value is scope since effector 22.0.0.

Returns

boolean — Type-guard

Examples

import { fork } from "effector";

const $store = createStore(null);
const event = createEvent();
const fx = createEffect();
const scope = fork();

is.scope(scope);
// => true

is.scope($store);
// => false

is.scope(event);
// => false

is.scope(fx);
// => false

is.scope(createDomain());
// => false

is.scope(null);
// => false

Try it

is.unit(value)

Checks if given value is Unit: Store, Event, Effect, Domain or Scope

Returns

boolean — Type-guard

Examples

import { is, createStore, createEvent, createEffect, createDomain, fork } from "effector";

const $store = createStore(null);
const event = createEvent();
const fx = createEffect();
const scope = fork();

is.unit(scope);
// => true

is.unit($store);
// => true

is.unit(event);
// => true

is.unit(fx);
// => true

is.unit(createDomain());
// => true

is.unit(fx.pending);
// => true

is.unit(fx.done);
// => true

is.unit($store.updates);
// => true

is.unit(null);
// => false

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is.attached(value)

Checks if given value is effect created via attach method. If passed not an effect, returns false.

Returns

boolean — Type-guard

Usage

Sometimes you need to add an error log on effects failures, but only on effects that have been “localized” via attach. If you leave onCreateEffect as it is, without checks, the error log will be duplicated, because it will happen on the parent and the child effect.

import { createDomain, attach, is } from "effector";

const logFailuresDomain = createDomain();

logFailuresDomain.onCreateEffect((effect) => {
  if (is.attached(effect)) {
    effect.fail.watch(({ params, error }) => {
      console.warn(`Effect "${effect.compositeName.fullName}" failed`, params, error);
    });
  }
});

const baseRequestFx = logFailuresDomain.createEffect((path) => {
  throw new Error(`path ${path}`);
});

const loadDataFx = attach({
  mapParams: () => "/data",
  effect: baseRequestFx,
});

const loadListFx = attach({
  mapParams: () => "/list",
  effect: baseRequestFx,
});

loadDataFx();
loadListFx();

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Examples

import { is, createStore, createEvent, createEffect, createDomain, attach } from "effector";

const $store = createStore(null);
const event = createEvent();
const fx = createEffect();

const childFx = attach({
  effect: fx,
});

is.attached(childFx);
// => true

is.attached(fx);
// => false

is.attached($store);
// => false

is.attached(event);
// => false

is.attached(createDomain());
// => false

is.attached(null);
// => false

Try it