***注意这里的$get是封装的axios方法
//方法一：
searchTopic() {
 return this.$axios({
       url:'地址1',
       method:'方式',//get/post/patch/put/deleted
       params:{//参数get所以用params。post.put用data
       }
      })
}
 //方法二：
searchs(){
     return this.$axios({
       url:'地址1',
       method:'方式',//get/post/patch/put/deleted
       params:{//参数get所以用params。post.put用data
       }
      })
     },
 
axios.all([searchTopic(), searchs()])
 .then(axios.spread(function (allSearchTopic, allSearchs) {
  debugger//打印可以拿到所有的返回值
  allSearchTopic == 方法一的返回值
  allSearchs == 方法二的返回值
 }));

function getUserAccount(){
 return axios.get('/user/12345');
}
function getUserPermissions(){
 return axios.get('/user/12345/permissions');
}
axios.all([getUserAccount(),getUserPermissions()])
 .then(axios.spread(function(acct,perms){
  //当这两个请求都完成的时候会触发这个函数，两个参数分别代表返回的结果
 }))

export const cargoDayNumber = (data) => {
 return axios.request({
  url: '/api/zz-xt/statistical/areas',
  method: 'post',
  data: data
 })
}

let r1 = carVisitTime({ createTime: '2019-06-27' })
   let r2 = statistic({ createTime: '2019-06-27' })
   let r3 = cargoDayNumber({ createTime: '2019-07-01' })
   let r4 = enterpriseRanking()
   axios.all([r1, r2, r3, r4]).then(
    axios.spread((r1, r2, r3, r4) => {
     
     this.numberVehicleVisits = r1.data      
     this.loadingDateRank.loading = r2.data.loading
     this.loadingDateRank.unloading = r2.data.unloading 
     
     this.loadingAreasRank.loadingRegionalList = r3.data.inflow
     this.loadingAreasRank.unloadingRegionalList = r3.data.outflow 
   
     this.enterpriseLoadWeight.enterpriseLoadingRankList = r4.data.loadingRank
     this.enterpriseLoadWeight.enterpriseUnloadingRankList = r4.data.unloadingRank
    })
   )

 Promise.all([p1, p2]).then(function(values) {
    console.log(values);//values为一个数组
    ///进行你的下一步操作
   });