微信小程序判断是否有上级页面栈

backToHall() {
    // 获取页面栈
    var pages = getCurrentPages();
    var curPages = pages[pages.length - 1]?.route;
    var prevPage = pages[pages.length - 2]?.route; // 无上级页面就是undefined
    console.log('curPages',curPages) // 完整地址：subE/pages/QTwo/pages/yzHome/videoTutorialPage/videoTutorialPage
    console.log('prevPage',prevPage)
  },