jotai-molecules

> jotai-molecules has been renamed to bunshi.
>
> All new users of this module should use bunshi instead. Bunshi
> adds support for vue, react and vanilla javascript. Development
> and features additions will continue under the bunshi package.
>
> Molecules in jotai-molecules version 1.2.0 are compatible with
> molecules from bunshi, and they can interoperated and depend on each
> others. Version 1.2.0 of jotai-molecules is just a wrapper for
> bunshi.
>
> Documentation: bunshi.org

A tiny, fast, dependency-free 1.18kb library for creating jotai atoms in a way that lets you lift state up, or push state down. See Motivation for more details on why we created this library.

Installation

This module is published on NPM as jotai-molecules

``sh
npm i jotai-molecules
`

> Note: Prefer bunshi to jotai-molecules

Usage

Molecules are a set of atoms that can be easily scoped globally or per context.

`tsx
import React from "react";
import { atom, useAtom } from "jotai";
import {
molecule,
useMolecule,
createScope,
ScopeProvider,
} from "jotai-molecules";

const CompanyScope = createScope("example.com");

const CompanyMolecule = molecule((_, getScope) => {
const company = getScope(CompanyScope);
const companyNameAtom = atom(company.toUpperCase());
return {
company,
companyNameAtom,
};
});

const UserScope = createScope("bob@example.com");

const UserMolecule = molecule((getMol, getScope) => {
const userId = getScope(UserScope);
const companyAtoms = getMol(CompanyMolecule);
const userNameAtom = atom(userId + " name");
const userCountryAtom = atom(userId + " country");
const groupAtom = atom((get) => {
return userId + " in " + get(companyAtoms.companyNameAtom);
});
return {
userId,
userCountryAtom,
userNameAtom,
groupAtom,
company: companyAtoms.company,
};
});

const App = () => (



);

const UserComponent = () => {
const userAtoms = useMolecule(UserMolecule);
const [userName, setUserName] = useAtom(userAtoms.userNameAtom);

return (



);
};
`

API

$3

Create a molecule that can be dependent on other molecules, or dependent on scope.

`ts
import { molecule } from "jotai-molecules";

export const PageMolecule = molecule(() => {
return {
currentPage: atom("/"),
currentParams: atom({}),
};
});
`

- Requires a getter function
- getMol - depend on the value of another molecule
- getScope - depend on the value of a scope

$3

Use a molecule for the current scope. Will produce a different value depending on the React context it is run in.

`tsx
import { useMolecule } from "jotai-molecules";
import { useSetAtom, useAtomValue } from "jotai";

export const PageComponent = () => {
const pageAtoms = useMolecule(PageMolecule);

const setParams = useSetAtom(pageAtoms.currentPage);
const page = useAtomValue(pageAtoms.currentPage);

return (



);
};
`

By default useMolecule will provide a molecule based off the _implicit_ scope from context. You can override this behaviour by passing options to useMolecule.

- withScope - will overide a scope value (ScopeTuple)
- withUniqueScope - will override a scope value with a new unique value (MoleculeScope)
- exclusiveScope - will override ALL scopes (ScopeTuple)

Instead of a scope provider, you can use an explicit scope when using a molecule. This can simplify integrating jotai with other hooks-based libraries.

Before:

`tsx
const App = () => (



);
`

After:

`tsx
useMolecule(UserMolecule, { withScope: [UserScope, "sam@example.com"] });
`

$3

Creates a reference for scopes, similar to React Context

`ts
import { createScope } from "jotai-molecules";

/**
* Scope for a user id
*/
export const UserScope = createScope("bob@example.com");
`

- initialValue the default value for molecules that depend on this scope

$3

Provides a new value for Scope, similar to React Context. This will create new molecules in the react tree that depend on it.

`tsx
const App = () => (



);
`

- scope the MoleculeScope reference to provide
- value` a new value for that scope