text: /**
   * Storage封装
   */
  const STORAGE_KEY = 'mall'
  export default {
    // 存储值
    setItem(key, value, module_name) {
      if (module_name) {
        let val = this.getItem(module_name);
        val[key] = value;
        this.setItem(module_name, val);
      } else {
        let val = this.getStorage();
        val[key] = value;
        window.sessionStorage.setItem(STORAGE_KEY, JSON.stringify(val));
      }
  
    },
    // 获取某一个模块下面的属性，user下面的userName
    getItem(key, module_name) {
      if (module_name) {
        let val = this.getItem(module_name);
        if (val) return val[key];
      }
      return this.getStorage()[key];
    },
    // 获取浏览器的缓存信息
    getStorage() {
      return JSON.parse(window.sessionStorage.getItem(STORAGE_KEY) || '{}');
    },
    // 删除
    clear(key,module_name) {
      let val = this.getStorage();
      if(module_name){
        if(!val[module_name][key]) return;  //val[module_name][key]二维数组，val数组下的module_name模块下的key
        delete val[module_name][key];
      }else{
        delete val[key];
      }
      window.sessionStorage.setItem(STORAGE_KEY, JSON.stringify(val));
    }
  }