javascript - promise nodejs 可读性改进

Question

我已经编写了一些返回 promise 的函数，以从 google analytics api 获取数据。我认为我所写的被称为回调 hell ..

有人可以帮助我优化此代码(或提供提示/最佳实践)，以提高可读性。

var express = require('express');
var router = express.Router();
var googleAuth = require('google-oauth-jwt');
var google = require('googleapis');
var app = express();

module.exports.getGoogleData = function (jwtClient,analytics,VIEW_ID){
  return new Promise(function(resolve, reject){
    return getOrdersToday(jwtClient,analytics,VIEW_ID).then(function (orders) {
      return getOnlineUsersToday(jwtClient,analytics,VIEW_ID).then(function (users) {
        return getSearchedToday(jwtClient, analytics, VIEW_ID).then(function (searched){
          return getPageviewsTodayAndUsersToday(jwtClient, analytics, VIEW_ID).then(function (pageviews){
            var returndata =[
              {
                "Orders":orders,
                "Onlineusers":users,
                "searched":searched,
                "pageviews":pageviews[0].pageviews,
                "usersToday":pageviews[0].users
              }
            ]
            resolve(returndata);
          });
        });
      });
    });
  });
}

示例获取函数

function getOrdersToday(jwtClient,analytics,view_id){
  return new Promise(function(resolve,reject){
    analytics.data.ga.get({
        'auth':jwtClient,
        'ids': view_id,
        'metrics': 'ga:totalEvents',
        'start-date': 'today',
        'end-date': 'today',
        filters: 'ga:eventAction==Bestelling geplaatst',
        'max-results': '1'
    }, function(err, response) {
          // handle the errors (if any)
          if(err){
            console.log(err)
            reject(err)
          } else
            console.log('Response:',response)
            resolve(response.totalsForAllResults["ga:totalEvents"]);
        });
    });
}

Answer 1

那里根本不需要 new Promise，事实上，通过使用它，如果您的调用之一发生错误，您可以让它保持开放状态，永远不会解决。请记住 then 返回一个新的 promise 。因此，如果您希望它们按顺序运行，您可以将所有这些链接在一起:

module.exports.getGoogleData = function (jwtClient,analytics,VIEW_ID){
  var result = {};
  return getOrdersToday(jwtClient,analytics,VIEW_ID)
    .then(function (orders) {
        result.Orders = orders;
        return getOnlineUsersToday(jwtClient,analytics,VIEW_ID);
    })
    .then(function (users) {
      result.Onlineusers = users;
      return getSearchedToday(jwtClient, analytics, VIEW_ID);
    }).then(function (searched){
      result.searched = searched;
      return getPageviewsTodayAndUsersToday(jwtClient, analytics, VIEW_ID);
    }).then(function (pageviews){
      result.pageviews = pageviews[0].pageviews;
      result.usersToday = pageviews[0].users;
      return [result]; // (Seems a bit odd that it's wrapped in an array, but
                       // that's what the original code did...)
    });
}

但是，这些操作看起来相互独立。如果这是真的，请与 Promise.all 并行运行它们:

module.exports.getGoogleData = function (jwtClient,analytics,VIEW_ID){
  return Promise.all([
    getOrdersToday(jwtClient,analytics,VIEW_ID),
    getOnlineUsersToday(jwtClient,analytics,VIEW_ID),
    getSearchedToday(jwtClient, analytics, VIEW_ID),
    getPageviewsTodayAndUsersToday(jwtClient, analytics, VIEW_ID)
  ]).then(results => {
    return [{
      Orders: results[0],
      Onlineusers: results[1],
      searched: results[2],
      pageviews: results[3][0].pageviews,
      usersToday: results[3][0].users
    }];
  });
}