@crikey/stores-strict

Provide svelte compatible implementations of readable, writable, derived and get with strict inequality triggering semantics.

Strict inequality triggering semantics provide a store version of the functionality seen with <svelte:options immutable={true} /> in the svelte compiler.

Strict equality stores make the most sense when programming with strict immutability rules and functional programming.

For complex structured immutable types, try @crikey/stores-immer

See @crikey/stores-strict for full documentation.

API

Store creation functions:

• constant - Create a Readable store with a fixed value
• readable - Create a Readable store
• writable - Create a Writable store
• derive - Create a Readable store derived from the resolved values of other stores
• transform- Create a Writable store by applying transform functions when reading and writing values

Utility functions:

• get - Retrieve the value of a store

Installation

# pnpm
$ pnpm add @crikey/stores-strict

# npm
$ npm add @crikey/stores-strict

# yarn
$ yarn add @crikey/stores-strict

Usage

Standard usage should be a drop in replacement for svelte/store, with the exception of when subscriptions are triggered.

Differences from svelte stores

Classic svelte stores signal for changes greedily. If a store value is updated and either the old or new value are complex types, then svelte will signal a change even if those values are strictly equal.

Strict stores use a simple referential inequality check (!==) to determine if a change signal should be sent.

e.g.

const store = writable([1]);

// log each change
store.subscribe(arr => console.log(arr));

// don't change anything
store.update(arr => {
    return arr;
});

// push an item onto the array
store.update(arr => {
    arr.push(2);
    return arr;
});

// @crikey/stores-strict
// > [1]
//
// @crikey/stores-svelte (svelte compatible stores)
// > [1]
// > [1]
// > [1,2]
//