StateHoldr

General localStorage saving for collections of state.

Usage

StateHoldr is targeted for use in games where discrete areas within the game map may contain separate changes. A house, for example, could contain a pot1 with { broken: boolean } that should be retrieved when the area loads and saved when left. This is referred to in StateHoldr as a "collection" of state.

Collections are serialized to JSON when switched into storage.

Constructor

const stateHolder = new StateHoldr();

collection

Starting collection to change within, if not "".

const stateHolder = new StateHoldr(
    collection: "house",
});

The collection can later be changed with .setCollection(collectionKey).

itemsHolder

Stores persistent changes locally. If not provided, a new ItemsHoldr() is used.

const itemsHolder = new ItemsHoldr();
const stateHolder = new StateHoldr({ itemsHolder });

prefix

Prefix to prepend to keys in storage. Collections are stored under the prefix concatenated with their name. A string[] of collection keys (excluding the prefix) is stored under the prefix concatenated with "collectionKeys" (exported from "stateholdr" as collectionKeysItemName).

const itemsHolder = new ItemsHoldr();
const stateHolder = new StateHoldr({
    collection: "house",
    itemsHolder,
    prefix: "MyStateHoldr::",
});

itemsHolder.getItem("MyStateHoldr::collectionKeys"); // ["house"]

addChange

Parameters:

• itemKey: string: Key of the item to add a change under.
• attribute: string: Attribute of the item being changed.
• value: any: Value under the attribute to change.

Adds a change to an object under the current collection.

stateHolder.addChange("pot1", "broken", true);

stateHolder.getChanges("pot1"); // { broken: true }

addChangeToCollection

Parameters:

• otherCollectionKey: string: Key of the collection to change within.
• itemKey: string: Key of the item to add a change under.
• attribute: string: Attribute of the item being changed.
• value: any: Value under the attribute to change.

Adds a change to an object under a named collection.

stateHolder.setCollection("outdoors");
stateHolder.getChanges("pot1"); // {}

stateHolder.addChangeToCollection("house", "pot1", "broken", true);
stateHolder.setCollection("house");

stateHolder.getChanges("pot1"); // { broken: true }

applyChanges

Parameters:

• itemKey: string: Key of a contained item.
• output: Object: Recipient for all the changes.

Copies all changes from a contained item into an output item. Useful when creating objects whose state is reflected by a collection's storage.

const pot = {};

stateHolder.addChange("pot1", "broken", true);
stateHolder.applyChanges("pot1", pot);

pot; // { broken: true }

getChanges

Parameters:

• itemKey: string: Key of a contained item.

Returns: Any changes under the itemKey, or {} if there were none.

stateHolder.addChange("pot1", "broken", true);

stateHolder.getChanges("pot1"); // { broken: true }

setCollection

Parameters:

• collectionKey: string: Key of a new collection to switch to.
• value: Object (optional): Container to override any existing state with.

Sets the currently tracked collection.

stateHolder.addChangeToCollection("house", "pot1", "broken", true);
stateHolder.setCollection("house");

stateHolder.getChanges("pot1"); // { broken: true }

The previous collection is saved to storage.

saveCollection

Saves the currently tracked collection into storage.

stateHolder.setCollection("house");
stateHolder.addChange("pot1", "broken", true);
itemsHolder.getItem("MyStateHoldr::house"); // {}

stateHolder.saveCollection();
itemsHolder.getItem("MyStateHoldr::house"); // { broken: true }

Development

This repository is a portion of the EightBittr monorepo. See its docs/Development.md for details on how to get started. 💖

Running Tests

yarn run test

Tests are written in Mocha and Chai. Their files are written using alongside source files under src/ and named *.test.ts?. Whenever you add, remove, or rename a *.test.t* file under src/, watch will re-run yarn run test:setup to regenerate the list of static test files in test/index.html. You can open that file in a browser to debug through the tests, or run yarn test:run to run them in headless Chrome.