bus.js

/**
 * EventBus 对象解决页面间的传值问题，在需要传值的页面引入这个文件
 *
 * 更新：9-29
 * tigger 后自动注销事件，不需要手动管理
 * 更新：10-20
 * 支持发布-订阅、订阅-发布两种模式
 * listen 第三个参数用于控制是否触发cache中的方法(为true开启订阅-发布模式)
 */
let EventBus = {};

Object.defineProperties(EventBus, {
  'cached': {
    value: {}
  },
  'handlers': {
    value: {}
  },
  'listen': {
    get() {
      return (event, ...options) => {
        let args = options[0]
        // 默认不使用cache。（缺省 undefined）
        let isCallCache = options[1];
        try {
          if (typeof args === 'function') {
            this._listen(event, args, isCallCache);
          } else {
            this._listen(event, args[event].bind(args), isCallCache)
          }
        } catch (e) {
          throw new Error(`${event} is not a function`)
        }
      }
    }
  },
  '_listen': {
    get() {
      return (event, fn, isCallCache) => {
        let handlers = this.handlers
        handlers[event] = fn
        if (this.cached[event] && isCallCache) {
          fn.apply(null, this.cached[event])
          delete this.cached[event]
        }
      }
    }
  },
  'remove': {
    get() {
      return (event, fn) => {
        let handlers = this.handlers[event]
        let cachedEvent = this.cached[event]
        if (!fn) {
          delete this.handlers[event]
          delete this.cached[event]
          return
        }
        for (let i = 0, len = handlers.length; i < len; i++) {
          if (handlers[i] === fn) {
            handlers.splice(i, 1)
            cachedEvent.splice(i, 1)
            break
          }
        }
      }
    }
  },
  'trigger': {
    get() {
      return (event, ...options) => {
        let handlers = this.handlers[event]
        if (handlers) {
          handlers.apply(null, options)
          delete this.handlers[event]
        }
        this.cached[event] = options
      }
    }
  }
})

export default EventBus