equals

import { equals } from 'patronum';
// or
import { equals } from 'patronum/equals';

Motivation

The method allows to compare store value with another value wrote as literal or contained in another store.

Formulae

$isEquals = equals(first, second);

$isEquals will be store with true if value in first and second is equals by comparing them with ===

Arguments

first: Store<T> | T — A value or the store to compare with second
second: Store<T> | T — A value or the store to be compared with first

Returns

$isEquals: Store<boolean> — The store contains true if values is equals

Example

const $first = createStore('foo bar');
const $isEquals = equals($first, 'foo bar');

console.assert(true === $isEquals.getState());

Try it

Composition

The equals operator can be composed with any other method of patronum:

const $account = createStore<Account | null>(null);
const $authorized = not(equals($account, null));
// $authorized contains `true` only when $account contains not `null`

Alternative

Compare to literal value:

import { createStore } from 'effector';
const $first = createStore('foo bar');
const $isEquals = $first.map((first) => first === 'foo bar');

console.assert(true === $isEquals.getState());

Compare to another store:

import { createStore, combine } from 'effector';
const $first = createStore('foo bar');
const $second = createStore('foo bar');
const $isEquals = combine($first, $second, (first, second) => first === second);

console.assert(true === $isEquals.getState());