微信小程序自定义 TabBar 实现红点提醒的完整方案

{
  "pages": [
    "pages/home/home",
    "pages/index/index",
    "pages/logs/logs"
  ],
  "window": {
    "navigationBarTextStyle": "black",
    "navigationBarTitleText": "Weixin",
    "navigationBarBackgroundColor": "#ffffff"
  },
  "componentFramework": "glass-easel",
  "sitemapLocation": "sitemap.json",
  "lazyCodeLoading": "requiredComponents",
  "usingComponents": {
    "van-button": "@vant/weapp/button/index",
    "my-numbers": "./components/numbers/numbers"
  },
  "tabBar": {
    "custom": true,
    "color": "#000000",
    "selectedColor": "#000000",
    "backgroundColor": "#ffffff",
    "list": [{
      "pagePath": "pages/home/home",
      "text": "组件"
    }, {
      "pagePath": "pages/index/index",
      "text": "接口"
    }]
  }
}

"usingComponents": {
  "van-tabbar": "@vant/weapp/tabbar/index",
  "van-tabbar-item": "@vant/weapp/tabbar-item/index"
}

<!--custom-tab-bar/index.wxml-->
<van-tabbar active="{{ active }}" bind:change="onChange">
  <van-tabbar-item info="3">
    <image
      slot="icon"
      src="{{ icon.normal }}"
      mode="aspectFit"
      style="width: 30px; height: 18px;"
      />
      <image
        slot="icon-active"
        src="{{ icon.active }}"
        mode="aspectFit"
        style="width: 30px; height: 18px;"
        />
        自定义
      </van-tabbar-item>
        <van-tabbar-item icon="search">标签</van-tabbar-item>
        <van-tabbar-item icon="setting-o">标签</van-tabbar-item>
      </van-tabbar>

// custom-tab-bar/index.js
Component({
  /**
   * 组件的属性列表
   */
  properties: {
  },
  /**
   * 组件的初始数据
   */
  data: {
    active: 0,
    icon: {
      normal: 'https://img.yzcdn.cn/vant/user-inactive.png',
      active: 'https://img.yzcdn.cn/vant/user-active.png',
    },
  },
  /**
   * 组件的方法列表
   */
  methods: {
    onChange(event) {
      this.setData({ active: event.detail });
    }
  }
})

// 在这个 js 文件中专门创建 store 对象
import {observable,action} from 'mobx-miniprogram'
export const store = observable({
  numA:1,
  numB:2,
  info:3,
  //计算属性
  get sum(){
    return this.numA+this.numB
  },
  //action方法用来修改 store 中的值
  updateNum1:action(function(step){
    this.numA+=step
  }),
  updateNum2:action(function(step){
    this.numB+=step
  }),
})

import { storeBindingsBehavior } from 'mobx-miniprogram-bindings';
import { store } from '../store/store';
Component({
  behaviors: [storeBindingsBehavior],
  properties: {},
  storeBindings: {
    store,
    fields: {
      numA: () => store.numA,
      numB: () => store.numB,
      sum: 'sum'
    },
    actions: {
      buttonTap: 'update'
    }
  },
  data: {
    info: 0,
    active: 0,
    icon: {
      normal: 'https://img.yzcdn.cn/vant/user-inactive.png',
      active: 'https://img.yzcdn.cn/vant/user-active.png',
    }
  },
  observers: {
    'sum': function(val) {
      this.setData({
        info: val
      });
    }
  },
  methods: {
    myMethod() {
      this.setData({
        info: this.data.sum
      });
    }
  }
});

<!--custom-tab-bar/index.wxml-->
<van-tabbar active="{{ active }}" bind:change="onChange">
  <van-tabbar-item info="{{numA}}">
    <image
      slot="icon"
      src="{{ icon.normal }}"
      mode="aspectFit"
      style="width: 30px; height: 18px;"
    />
    <image
      slot="icon-active"
      src="{{ icon.active }}"
      mode="aspectFit"
      style="width: 30px; height: 18px;"
    />
    自定义
  </van-tabbar-item>
  <van-tabbar-item icon="search">标签</van-tabbar-item>
  <van-tabbar-item icon="setting-o">标签</van-tabbar-item>
</van-tabbar>