@lumieslab/stasho/dist/store.js

lightweight state management library

"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.Store = void 0;
/**
 * Creates a store that can be used to manage state and dispatch actions.
 * @param initialState the initial state of the store
 * @param reducers a list of reducers that will be applied to the state
 * @param memories a list of memory which computes the state
 * @param effects a list of effects that occur when an action is dispatched
 * @constructor
 */
const Store = (initialState, reducers = [], memories = [], effects = []) => {
    let state = initialState;
    const memoryState = new Map();
    const updateMemories = () => {
        memories.forEach((memory) => {
            memoryState.set(memory, memory(state));
        });
    };
    // Dispatch a change
    const dispatch = (action) => {
        // Reduce all the states though the action and produce new
        state = reducers.reduce((state, reducerCallback) => reducerCallback(state, action), state);
        // Update memory state
        updateMemories();
        // Call effects on all systems
        effects.forEach((effectCallback) => effectCallback(action));
    };
    // Returns the memory item using the reference to the memory callback.
    const getMemory = (reference) => {
        return memoryState.get(reference);
    };
    // Attaches the reducer callback to the array of reducers
    const attachReducer = function (reducerCallback) {
        reducers.push(reducerCallback);
    };
    // Attaches the memory callback to the array of memories
    const attachMemory = function (memoryCallback) {
        memories.push(memoryCallback);
        updateMemories();
    };
    // Attaches the effect callback to the array of effects
    const attachEffect = function (effectCallback) {
        effects.push(effectCallback);
    };
    // Initialise the state of the store
    updateMemories();
    // Controls to interact with store
    return {
        dispatch,
        getMemory,
        attachReducer,
        attachMemory,
        attachEffect
    };
};
exports.Store = Store;