react-entities/src/utils.js

React Entities - the simplest app state management for React

/* Basic selectors */
export const selectAll = state => state;
export const selectNone = _ => null;

/* Basic equality functions */
export const strictEqual = (a, b) => a === b;
export const shallowEqual = (a, b) =>
  strictEqual(a, b) || (bothObjects(a, b) && equalProps(a, b));

const bothObjects = (a, b) =>
  typeof a === 'object' && a !== null && typeof b === 'object' && b !== null;

const equalProps = (a, b) => {
  const keysOfA = Object.keys(a);
  const keysOfB = Object.keys(b);
  if (keysOfA.length !== keysOfB.length) return false;
  for (let i = 0; i < keysOfA.length; i++) {
    const key = keysOfA[i];
    if (!b.hasOwnProperty(key) || a[key] !== b[key]) return false;
  }
  return true;
};