微信小程序小红点未读消息如何实现？

data: {

userInfo: {},

projectSource: 'https://github.com/liuxuanqiang/wechat-weapp-mall',

userListInfo: [ {

icon: '../../images/iconfont-dingdan.png',

text: '我的订单',

isunread: true,

unreadNum: 2

}, {

icon: '../../images/iconfont-card.png',

text: '我的代金券',

isunread: false,

unreadNum: 2

}, {

icon: '../../images/iconfont-icontuan.png',

text: '我的拼团',

isunread: true,

unreadNum: 1

}, {

icon: '../../images/iconfont-shouhuodizhi.png',

text: '收货地址管理'

}, {

icon: '../../images/iconfont-kefu.png',

text: '联系客服'

}, {

icon: '../../images/iconfont-help.png',

text: '常见问题'

}]

},

这些数据从服务器获取后，setData