Vue监听sessionStorage

1. main.js
   Vue.prototype.$setStorageItem = function (key, newVal) {
   //activeIndex监听的session字段
   if (key === 'activeIndex') {
   // 创建一个StorageEvent事件
   var newStorageEvent = document.createEvent('StorageEvent');
   const storage = {
   setItem: function (k, val) {
   sessionStorage.setItem(k, val);
   // 初始化创建的事件
   newStorageEvent.initStorageEvent('setItem', false, false, k, null, val, null, null);
   // 派发对象
   window.dispatchEvent(newStorageEvent)
   }
   }
   return storage.setItem(key, newVal);
   }
   }

2. created或mounted
   window.addEventListener('setItem', () => {
   this.setActiveIndex(sessionStorage.getItem('activeIndex') || '3')

})

3. 设置值
   this.$setStorageItem('activeIndex', key)