index.js

const check = (origin, cache, count) => {
  if (process.env.NODE_ENV !== 'production') {
    for (let key in origin) {
      if (cache.indexOf(key) === -1) {
        cache.push(key);
      } else {
        count[key] ? count[key]++ : count[key] = 1;
      }
    }
  }
}

const log = (model, constitute, count) => {
  if (process.env.NODE_ENV !== 'production') {
    let logCount = 0;
    for (let key in count) {
      if (!logCount) {
        console.warn(`Please note that some of the attributes are inherited in the ${model.namespace} / ${constitute}:`);
      }
      logCount++;
      console.warn(`  -> ${key} be overwritten ${count[key]} time(s).`);
    }
  }
}

// 实现深拷贝的Object.assign
const deepObjectAssign = (target, source) => {
  try {
    if (source) {
      // 对source进行判空，否则JSON.parse操作会报错： Unexpected token u in JSON at position 0
      Object.assign(target, JSON.parse(JSON.stringify(source)))
    }
  } catch (e) {
    console.log(e)
  }
}

export default function modelExtend(...models) {
  const base = { state: {}, subscriptions: {}, effects: {}, reducers: {}, };
  const stateCache = [];
  const stateCount = {};
  const subscriptionsCache = [];
  const subscriptionsCount = {};
  const effectsCache = [];
  const effectsCount = {};
  const reducersCache = [];
  const reducersCount = {};

  const model = models.reduce((acc, extend) => {
    acc.namespace = extend.namespace;
    if (typeof extend.state === 'object' && !Array.isArray(extend.state)) {
      check(extend.state, stateCache, stateCount)
      deepObjectAssign(acc.state, extend.state);
    } else if ('state' in extend) {
      acc.state = extend.state;
    }
    check(extend.subscriptions, subscriptionsCache, subscriptionsCount)
    Object.assign(acc.subscriptions, extend.subscriptions);
    check(extend.effects, effectsCache, effectsCount)
    Object.assign(acc.effects, extend.effects);
    check(extend.reducers, reducersCache, reducersCount)
    Object.assign(acc.reducers, extend.reducers);
    return acc;
  }, base);

  log(model, 'state', stateCount)
  log(model, 'subscriptions', subscriptionsCount)
  log(model, 'effects', effectsCount)
  log(model, 'reducers', reducersCount)
  return model;
};