proxy to map the selector path

meta-store.ts

import { createSelector } from "starfx/store";

/* SELECTORS */
/**
 * Creates a proxy around an object to track accessed properties.
 *
 * @param {object} obj - The object to create a proxy for.
 * @returns {[object, Set<string>]} An array containing the proxy object and a Set of accessed property names.
 */
function trackAccesses(obj) {
  const accessedProps = new Set();
  const handler = {
    get(target, prop) {
      accessedProps.add(prop);
      return target[prop];
    },
  };
  return [new Proxy(obj, handler), accessedProps];
}

/**
 * Creates a selector that captures the accessed data slices and treats them as paths.
 * Applies the error state to the data selector and retrieves
 * the error messages from the corresponding paths.
 *
 * @param {function} dataSelector - The original data selector function.
 * @returns {function} A modified error selector function.
 */
export const metaSelector = (dataSelector) => {
  return createSelector(
    (dataState) => dataState,
    (dataState) => {
      try {
        // Collects the accessed data slices as path-like information
        const [stateProxy, accessedSlices] = trackAccesses(dataState);
        // Invokes the data selector to capture relevant slices
        const _ = dataSelector(stateProxy);
        // Retrieves the current error/messate state
        const metaState = window.metaFx.getState();
        // Filters accessed slices for existing error states and maps to messages
        const errors = Array.from(accessedSlices)
          .filter((slice: string) => metaState[slice])
          .map((slice: string) => metaState[slice]);
        // Returns the found error messages (if any)
        return errors.length > 0 ? errors : [];
      } catch (e) {
        console.log(e);
        return [e.message];
      }
    }
  );
};