微信小程序之-返回上一页

wxml:    bindtap="navigateBack"js:  navigateBack: function () {    var self = this;    var pages = getCurrentPages();    if (pages.length == 1) {      if (self.data.circleId && self.data.circleId >0) {        wx.redirectTo({          url: '../../circle/index/index?circleId=' + self.data.circleId          + '&circleName=' + (self.data.circleName || '')        });      } else {        wx.switchTab({          url: "../../home/grouplist/grouplist"        });      }    } else {      wx.navigateBack({ changed: true });    }  },