createEvent

import { createEvent } from "effector";


const event = createEvent();

Method for creating events.

Formula

createEvent<E = void>(eventName?: string): EventCallable<E>
createEvent<E = void>(config: {
  name?: string
  sid?: string
  domain?: Domain
}): EventCallable<E>

  • Arguments

    • eventName: Optional argument. Event name for debugging.

    • config: Optional argument. Configuration object.

      • name: Event name.
      • sid: Stable identifier for SSR.
      • domain: Domain for the event.

  • Return value

Returns a new callable event.

Examples

Updating state by calling an event:

import { createStore, createEvent } from "effector";


const addNumber = createEvent();


const $counter = createStore(0);


$counter.on(addNumber, (state, number) => state + number);


$counter.watch((state) => {
  console.log("state", state);
});
// => 0


addNumber(10);
// => 10


addNumber(10);
// => 20


addNumber(10);
// => 30

Run example

We created the addNumber event and the $counter store, then subscribed to store updates.
Notice the function call addNumber(10). Every time you call addNumber(10), you can check the console and see how the state changes.

Processing data with derived events:

import { createEvent } from "effector";


const extractPartOfArray = createEvent();
const array = extractPartOfArray.map((arr) => arr.slice(2));


array.watch((part) => {
  console.log(part);
});
extractPartOfArray([1, 2, 3, 4, 5, 6]);
// => [3, 4, 5, 6]

Run example

Common errors

Below is a list of possible errors you may encounter when working with events:

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