A页面

onTotalUnreadMessageCountUpdated (event){
				this.globalData.totalUnreadCount=event.data
				uni.$emit('totalUnreadCount',{totalUnreadCount:event.data})
},

B页面

getNum(){
				let self=this
				uni.$on('totalUnreadCount',function(data){
					// if(data.totalUnreadCount==0) return
						this.$nextTick(()=>{
							self.totalUnreadCount= data.totalUnreadCount
						})
					})
			},

使用 this.$nextTick()即可重新渲染当前页面