装饰器

装饰器

/**
 * 为dom元素添加事件
 * @param {} dom
 * @param {*} type
 * @param {*} fn
 */
function addEvent(dom, type, fn) {
  if (dom.addEventListener) {
    dom.addEventListener(type, fn, false)
  } else if (dom.attachEvent) {
    dom.attachEvent("on" + type, fn)
  } else {
    dom["on" + type] = fn
  }
}

/**
 * 装饰已有对象
 * @param {*} id
 * @param {*} fn
 */
function decorator(id, fn) {
  let obj = document.querySelector(id)
  if (typeof id.onclick === "function") {
    let oldFn = id.onclick
    id.onclick = function () {
      oldFn()
      fn()
    }
  } else {
    obj.onclick = fn
  }
}

观察者模式

let Observer = (() => {
  let _message = {}
  return {
    regist: function (type, fn) {
      if (typeof _message[type] === "undefined") {
        _message[type] = [fn]
      } else {
        _message[type].push(fn)
      }
    },
    fire: function (type, args) {
      if (!_message[type]) {
        return
      }
      let events = {
        type,
        args: args || {},
      }
      for (let i = 0, len = _message[type].length; i < len; i++) {
        _message[type][i].call(this, events)
      }
    },
    remove: function (type, fn) {
      if (_message[type] instanceof Array) {
        for (let i = _message[type].length - 1; i >= 0; i--) {
          _message[type][i] === fn && _message[type].splice(i, 1)
        }
      }
    },
  }
})()

Observer.regist("test", function (e) {
  // register
  console.log(e.type, e.args.msg)
})
Observer.fire("test", { msg: "this is some test message" }) // send