如何利用 JavaScript 实现一个简单的依赖注入容器来管理模块依赖？

class Container {
  constructor() {
    this._registry = new Map();
  }

  register(key, resolver) {
    this._registry.set(key, resolver);
  }

  resolve(key) {
    if (!this._registry.has(key)) {
      throw new Error(`No dependency registered for key: ${key}`);
    }

    const resolver = this._registry.get(key);
    return typeof resolver === 'function' ? resolver(this) : resolver;
  }
}

// 假设有两个服务
class Logger {
  log(msg) {
    console.log(`[LOG] ${msg}`);
  }
}

class UserService {
  constructor(container) {
    this.logger = container.resolve('logger');
  }

  createUser(name) {
    this.logger.log(`Creating user: ${name}`);
    return { id: Date.now(), name };
  }
}

// 使用容器注册
const container = new Container();

container.register('logger', () => new Logger());
container.register('userService', (container) => new UserService(container));

// 解析使用
const userService = container.resolve('userService');
userService.createUser('Alice');

class Container {
  constructor() {
    this._registry = new Map();
    this._instances = new Map(); // 缓存单例
  }

  register(key, resolver, singleton = false) {
    this._registry.set(key, { resolver, singleton });
  }

  resolve(key) {
    if (!this._registry.has(key)) {
      throw new Error(`No dependency registered for key: ${key}`);
    }

    const { resolver, singleton } = this._registry.get(key);

    if (singleton && this._instances.has(key)) {
      return this._instances.get(key);
    }

    const value = typeof resolver === 'function' ? resolver(this) : resolver;
    if (singleton) {
      this._instances.set(key, value);
    }

    return value;
  }
}

container.register('logger', () => new Logger(), true);
container.register('userService', (container) => new UserService(container), true);