使用 vue 实例更好的监听事件

created () {
  this.$el.addEventListener('click', this.someMethod)
},
destroyed () {
  this.$el.removeEventListener('click', () => this.someMethod)
}

import Vue from 'vue'

const WindowInstanceMap = new Vue({
  data() {
    return {
      scrollY: 0
    }
  },
  created() {
    window.addEventListener('scroll', e => {
      this.scrollY = window.scrollY
    })
  },
})

export default WindowInstanceMap

// AppNav.vue
import WindowInstanceMap from './WindowInstanceMap.js'
export default {
  computed: {
    scrollY () { return WindowInstanceMap.scrollY },
    isCollapsed () {
      return this.scrollY < 100
    }
  }
}