grave/custom-tab-bar/index.js

let tabBar = {
  "custom": true,
  "backgroundColor": "#fff",
  "borderStyle": "black",
  "selectedColor": "#ED5D18",
  "color": "#666C7D",
  "list": [
    {
      "pagePath": "/pages/index/index",
      "iconPath": "/static/images/hbtab_home@2x.png",
      "selectedIconPath": "/static/images/btab_home@2x.png",
      "text": "店铺"
    },
    {
      "pagePath": "/pages/catalog/catalog",
      "iconPath": "/static/images/hbtab_classify@2x.png",
      "selectedIconPath": "/static/images/btab_classify@2x.png",
      "text": "分类"
    },
    {
      "pagePath": "/pages/discover/discover",
      "iconPath": "/static/images/btab_view@2x.png",
      "selectedIconPath": "/static/images/btab_view_active@2x.png",
      "keyiconPath": "/static/images/key_btab_view@2x.png",
      "text": "发现",
      "keynote": true
    },
    {
      "pagePath": "/pages/cart/cart",
      "iconPath": "/static/images/hbtab_cart@2x.png",
      "selectedIconPath": "/static/images/btab_cart@2x.png",
      "text": "购物车"
    },
    {
      "pagePath": "/pages/ucenter/index/index",
      "iconPath": "/static/images/hbtab_my@2x.png",
      "selectedIconPath": "/static/images/btab_my@2x.png",
      "text": "我的"
    }
  ]
}

let selectIndex = 2
let fns = []
let setCountFns = []

global.setTabBarBadge = function(args) {
  setCountFns.forEach(fn => fn(args))
}

Component({
  data: {
    tips: {},
    selectIndex,
    color: tabBar.color,
    selectedColor: tabBar.selectedColor,
    backgroundColor: tabBar.backgroundColor,
    borderStyle: tabBar.borderStyle,
    list: tabBar.list
  },
  attached() {
    setCountFns.push((args) => {
      this.setData({
        tips: {
          index: args.index, 
          count: args.text
        }
      })
    })
    fns.push(() => this.setData({ selectIndex }))
    fns.forEach(fn => fn())
  },
  methods: {
    switchTab(e) {
      const data = e.currentTarget.dataset
      const url = data.path
      wx.switchTab({url})
      this.setData({
        selectIndex: data.index
      })
      selectIndex = data.index

      fns.forEach(fn => fn())
    }
  }
})