puppeteer知识汇总

定义对象间的一种一对多的依赖关系，当一个对象的状态发生改变时，所有依赖于它的对象都将得到通知。

// 发布订阅模式 EventBus.js
let instance = null
const listeners = {}

class EventBus {
  static getInstance = () => {
    if (instance) {
      return instance
    }
    instance = new EventBus()
    return instance
  }

  on = (event, fn) => {
    if (listeners[event]) {
      listeners[event].push(fn)
    } else {
      listeners[event] = [fn]
    }
  }

  emit = (event, data) => {
    try {
      listeners[event].map(fn => fn(data))
    } catch (error) {
      throw error
    }
  }

  off = (event) => {
    delete listeners[event]
  }
}

const eventBus = EventBus.getInstance();

// 使用
eventBus.on('click', (data) => {
  console.log(data)
})

eventBus.emit('click', 1000)

eventBus.off('click')

export default eventBus;