js 集合添加事件

function createArrayObserver(array, callback) {
  return new Proxy(array, {
    set(target, prop, value) {
      const result = Reflect.set(target, prop, value);
      callback();
      return result;
    },
    deleteProperty(target, prop) {
      const result = Reflect.deleteProperty(target, prop);
      callback();
      return result;
    }
  });
}

const myArray = [];
const observedArray = createArrayObserver(myArray, () => {
  console.log('Array changed!');
});

observedArray.push(1); // 输出 "Array changed!"
observedArray[0] = 2; // 输出 "Array changed!"
delete observedArray[0]; // 输出 "Array changed!"

class ObservableArray {
  constructor() {
    this.array = [];
    this.listeners = [];
  }

  addListener(listener) {
    this.listeners.push(listener);
  }

  removeListener(listener) {
    this.listeners = this.listeners.filter(l => l !== listener);
  }

  push(item) {
    this.array.push(item);
    this.notifyListeners();
  }

  // ... 其他数组方法

  notifyListeners() {
    this.listeners.forEach(listener => listener(this.array));
  }
}

const observableArray = new ObservableArray();
observableArray.addListener(arr => {
  console.log('Array changed!', arr);
});

observableArray.push(1); // 输出 "Array changed! [1]"