JavaScript第三方库delegates的用法详解

npm install delegates
# 或
yarn add delegates

const Delegate = require('delegates');

class Server {
  constructor() {
    this.settings = { env: 'development' };
  }

  listen(port) {
    console.log(`Server listening on port ${port}`);
  }
}

class Koa {
  constructor() {
    this.server = new Server();
    Delegate(this, 'server')
      .method('listen')
      .access('settings');
  }
}

const app = new Koa();
app.listen(3000);
console.log(app.settings.env);

const Delegate = require('delegates');

class Store {
  constructor() {
    this.data = {};
  }

  set(key, value) {
    this.data[key] = value;
  }

  get(key) {
    return this.data[key];
  }

  has(key) {
    return Object.prototype.hasOwnProperty.call(this.data, key);
  }
}

class Controller {
  constructor() {
    this.store = new Store();
    Delegate(this, 'store')
      .method('set')
      .method('get')
      .method('has');
  }
}

const ctrl = new Controller();
ctrl.set('user', { name: 'Alice' });
console.log(ctrl.has('user'));  // 输出: true

const Delegate = require('delegates');

class Original {
  a() { console.log('a method'); }
  b() { console.log('b method'); }
  c() { console.log('c method'); }
  // ...更多方法
}

class Proxy {
  constructor() {
    this.original = new Original();
    const methods = Object.getOwnPropertyNames(Original.prototype).filter(
      prop => typeof this.original[prop] === 'function' && prop !== 'constructor'
    );

    methods.forEach(method => Delegate(this, 'original').method(method));
  }
}

const proxy = new Proxy();
proxy.a();  // 输出: a method
proxy.b();  // 输出: b method
proxy.c();  // 输出: c method