javascript - express 中间件被执行了两次

Question

我写了一个中间件来更新我在缓存中的一些变量，所以如果数据应该过期它会更新但实际上发生了两次并且不是 chrome，我使用的是 firefox。这是我的服务器 js 文件(我评论了 mustache express as templates 以确保它不是因为它):

const express = require('express') ;

const path = require('path');
var mustacheExpress = require('mustache-express');
var request = require('request');
var {updateAllDecks} = require('./utils/deck-request');
var cache = require('memory-cache');

const port = process.env.PORT || 3000;
var app = express();    

// Register '.html' extension with The Mustache Express
app.engine('html', mustacheExpress());
app.set('view engine','mustache');

app.set('views', __dirname + '/views');

//const publicPath = path.join(__dirname, '/public');
//app.use('/', express.static(publicPath));

app.use(function (req, res, next) {
  debugger;
  updateAllDecks(next);
})

app.get('/', (req, res) => {
     res.send('hola');
});

app.listen(port, () => {
  console.log(`Server is up on port ${port}`);
});

所以当我通过浏览器转到“/”时，应该调用 updateAllDecks():

var rp = require('request-promise-native');
var cache = require('memory-cache');
var {Deck} = require('../classes/deck');
var cacheDeck = require('./cache-decks');
var moment = require('moment');


var updateDeck =  async (set,resolve) => {
  //console.log(`${cacheDeck.getCachedExpirationDate(set)}  > ${moment(Date.now()).unix()}`);

    if (cacheDeck.getCachedExpirationDate(set) > moment(Date.now()).unix()) {
      //let deck =  await getDeckCached(set);
      console.log('Cached Deck Back');
      resolve();

    } else {
      let url = `https://playartifact.com/cardset/${set}/`;
      console.log('Getting URL');
      response = await  rp({url:url, json: true});
      var deck = new Deck(set, response.expire_time);
      getDeckRequest(deck,response,resolve)

    }


}

var getDeckRequest =  async (deck, body,resolve) => {
    console.log('Caching deck', deck);
    response = await rp({url:body.cdn_root + body.url.substring(1), json: true});
    deck.setName(response.card_set.set_info.name.english);
    deck.setCards(response.card_set.card_list);
    cacheDeck.addDeck(deck);
    console.log(cacheDeck.getCachedDecksNames());
    resolve();

}

var getDeckCached = (id) => {
  return new Promise((resolve,reject) =>  {
      resolve(cacheDeck.getCachedDeckById(id));
  });
}

var updateAllDecks = (callback) => {

  let decks = [0,1];
  var request = decks.map((deck) =>  {
    return new Promise( (resolve) => {
       updateDeck(deck,resolve);
    });

  });

  Promise.all(request).then(() => {
    callback();
    console.log('Finished');
  });
};

module.exports = {updateAllDecks}

回调();在 updateAllDecks() 函数中是 next() 调用以推进显示页面。

Answer 1

在中间件函数中添加了这行代码以了解调用的内容。

console.log(req.method, req.path)

原来是浏览器调用服务器获取favicon，使express调用中间件。