获取头部信息

 // 获取头部信息
  onGetTop() {
    const systemInfo = wx.getSystemInfoSync();
    const menuButtonInfo = wx.getMenuButtonBoundingClientRect();
    this.setData({
      navBarHeight:
        (menuButtonInfo.top - systemInfo.statusBarHeight) * 2 +
        menuButtonInfo.height +
        systemInfo.statusBarHeight
    });
  }