sessionStorage 封装

const TokenKey = "THIS_SESSION-STORAGE_NOT_DEL"

**读取**
export function getToken(){
  return sessionStorage.getItem(TokenKey)
}

**设置**
export function setToken(token){
  return sessionStorage.setItem(TokenKey, token)
}

**删除**

export function removeToken(){
  return sessionStorage.removeItem(TokenKey)
}