share_activity/components/topbar.js

// components/topbar.js
Component({
    /**
     * 组件的属性列表
     */
    properties: {

    },

    /**
     * 组件的初始数据
     */
    data: {

    },

    attached: function() {
        var url =getCurrentPages()[getCurrentPages().length-1].route

        let dwObj = wx.getMenuButtonBoundingClientRect()
        let navHeight_ = (dwObj.top + dwObj.height)
        let capsuleTop_ = dwObj.top
        let windowHeight = wx.getSystemInfoSync().windowHeight

        this.setData({
            navHeight: navHeight_,
            capsuleTop:capsuleTop_, 
            capHeight: dwObj.height,
            bodyHeight: windowHeight - navHeight_,
        });
    },

    /**
     * 组件的方法列表
     */
    methods: {
        handleBack() {
            let routeLen = getCurrentPages().length;
            if (routeLen == 1) {
                wx.reLaunch({
                  url: '/pages/welfareMall/index/index',
                })
                return
            }
            const url =getCurrentPages()[getCurrentPages().length-2].route
            wx.switchTab({
              url: "/" + url,
            })
        }
    }
})