以 vue-element-admin 说明

1、在layout/mixin/ResizeHandler.js 进行了全局的屏幕大小的watch,

 当屏幕大小发生改变时 会把变量写到 状态管理器vuex中：

然后在需要自适应的页面可以：

v-if=device=='mobile' 判断是否是手机端。

-----
 <template v-if="device!=='mobile'">

</template>

...
<script>
 expor default{
....
 computed: {
    ...mapGetters([
      'sidebar',
      'avatar',
      'device'
    ])
  },
}
-----

 layout/mixin/ResizeHandler.js

import store from '@/store'

/**
 * 手机和移动端的监测工具类
 * 
 */
const { body } = document
const WIDTH = 992 // refer to Bootstrap's responsive design

export default {
  watch: {
    $route(route) {
      if (this.device === 'mobile' && this.sidebar.opened) {
        store.dispatch('app/closeSideBar', { withoutAnimation: false })
      }
    }
  },
  beforeMount() {
    window.addEventListener('resize', this.$_resizeHandler)
  },
  beforeDestroy() {
    window.removeEventListener('resize', this.$_resizeHandler)
  },
  mounted() {
    const isMobile = this.$_isMobile()
    if (isMobile) {
      store.dispatch('app/toggleDevice', 'mobile')
      store.dispatch('app/closeSideBar', { withoutAnimation: true })
    }
  },
  methods: {
    // use $_ for mixins properties
    // https://vuejs.org/v2/style-guide/index.html#Private-property-names-essential
    $_isMobile() {
      const rect = body.getBoundingClientRect()
      return rect.width - 1 < WIDTH
    },
    $_resizeHandler() {
      if (!document.hidden) {
        const isMobile = this.$_isMobile()
        store.dispatch('app/toggleDevice', isMobile ? 'mobile' : 'desktop')

        if (isMobile) {
          store.dispatch('app/closeSideBar', { withoutAnimation: true })
        }
      }
    }
  }
}

store/getters.js

const getters = {
  sidebar: state => state.app.sidebar,
  language: state => state.app.language,
  size: state => state.app.size,
  device: state => state.app.device,
  visitedViews: state => state.tagsView.visitedViews,
  cachedViews: state => state.tagsView.cachedViews,
  token: state => state.user.token,
  avatar: state => state.user.avatar,
  name: state => state.user.name,
  introduction: state => state.user.introduction,
  roles: state => state.user.roles,
  permission_routes: state => state.permission.routes,
  errorLogs: state => state.errorLog.logs
}
export default getters