Cache a function result in SessionStorage (no matter the properties)

caching.js

import _ from 'lodash';

/**
 * Wraps a function to cache the result
 * no matter what props are passed
 * only caches the result if it isn't empty
 *
 * This is just using a closure for caching.
 * If the function is declared again, the value will be lost.
 */
export const cacheFunctionResult = (func, key) => {
  return (props) => {
    const cached = sessionStorage.getItem(key);
    console.log(key, cached);
    if (cached) {
      console.log('using cached value');
      return JSON.parse(cached);
    }
    const result = func(props);
    if (!_.isEmpty(result)) {
      console.log('caching result');
      sessionStorage.setItem(key, JSON.stringify(result));
    }
    return result;
  };
};

caching.spec.js

import { cacheFunctionResult } from './caching';

describe('Testing Caching Wrapper', () => {
  test('Stores result when result is not empty', () => {
    const mockFunction = jest.fn((x) => [x, x]);
    const cachedFunc = cacheFunctionResult(mockFunction, 'test');

    // Sanity check
    sessionStorage.setItem('testing', 2);
    expect(sessionStorage.getItem('testing')).toEqual('2');

    // Run the function initially
    let result = cachedFunc(2);
    expect(result).toEqual([2, 2]);
    // Get the cached result for the same prop
    result = cachedFunc(2);
    expect(result).toEqual([2, 2]);
    // Get the cached result for a different prop
    result = cachedFunc(1);
    expect(result).toEqual([2, 2]);

    expect(mockFunction.mock.calls.length).toBe(1);
  });
});