微信小程序 A页到B页，B页传值到A页

var pages = getCurrentPages();

    var content = this.data.content;

    var attachments = this.data.attachments;

    if (content.length == 0 && attachments.length == 1) {

      wx.showModal({

        content: '请输入发布文本或添加附件',

        showCancel: false,

        confirmText: "确定",

      })

      return;

    }

    if (pages.length >= 2) {

      var prevPage = pages[pages.length - 2];  //上一个页面

      var publishData = {};

      if (content.length > 0) {

        publishData.content = content;

      }

      if (attachments.length > 0) {

        attachments.splice(attachments.length - 1, 1);

      }

      publishData.attachments = attachments;

      //直接调用上一个页面的setData()方法，把数据存到上一个页面中去

      prevPage.setData({

        publishData: publishData

      })

      wx.navigateBack();

    }