Javascript地图，明年开始之前等待前面的承诺？

我知道这是不是在Array.map的范围，但我想等到前一个项目已经开始下一个之前完成其承诺。碰巧，我需要等待前一个条目向前移动之前被保存在数据库中。

const statsPromise = stats.map((item) => {
    return playersApi.getOrAddPlayer(item, clubInfo, year); //I need these to wait until previous has finished its promise.
});

Promise.all(statsPromise)
.then((teamData) => {
  ..//
});

playersApi.getOrAddPlayer返回new Promise

编辑

阅读更多有关它，似乎它的重要展示playersApi.getOrAddPlayer

getOrAddPlayer: function (item, clubInfo, year) {
    return new Promise((resolve, reject) => {

        var playerName = item.name.split(' '),
            fname = playerName[0].caps(),
            sname = playerName[1].caps();

                Players.find({
                    fname: fname,
                    sname: sname,
                }).exec()
                .then(function(playerDetails, err){
                    if(err) reject(err);
                    var savePlayer = new Players();
                    //stuff
                    savePlayer.save()
                    .then(function(data, err){
                        if(err)  reject(err);
                        item._id = data._id;
                        resolve(item);
                    });
                });
            });
}

您可以使用减少，而不是映射来实现：

stats.reduce(
  (chain, item) =>
    // append the promise creating function to the chain
    chain.then(() => playersApi.getOrAddPlayer(item, clubInfo, year)),
  // start the promise chain from a resolved promise
  Promise.resolve()
).then(() => 
  // all finished, one after the other
);

示范：

const timeoutPromise = x => {
  console.log(`starting ${x}`);
  return new Promise(resolve => setTimeout(() => {
    console.log(`resolving ${x}`);
    resolve(x);
  }, Math.random() * 2000));
};

[1, 2, 3].reduce(
  (chain, item) => chain.then(() => timeoutPromise(item)),
  Promise.resolve()
).then(() =>
  console.log('all finished, one after the other')
);

Javascript地图，明年开始之前等待前面的承诺？

我知道这是不是在Array.map的范围，但我想等到前一个项目已经开始下一个之前完成其承诺。碰巧，我需要等待前一个条目向前移动之前被保存在数据库中。

const statsPromise = stats.map((item) => {
    return playersApi.getOrAddPlayer(item, clubInfo, year); //I need these to wait until previous has finished its promise.
});

Promise.all(statsPromise)
.then((teamData) => {
  ..//
});

playersApi.getOrAddPlayer返回new Promise

编辑

阅读更多有关它，似乎它的重要展示playersApi.getOrAddPlayer

getOrAddPlayer: function (item, clubInfo, year) {
    return new Promise((resolve, reject) => {

        var playerName = item.name.split(' '),
            fname = playerName[0].caps(),
            sname = playerName[1].caps();

                Players.find({
                    fname: fname,
                    sname: sname,
                }).exec()
                .then(function(playerDetails, err){
                    if(err) reject(err);
                    var savePlayer = new Players();
                    //stuff
                    savePlayer.save()
                    .then(function(data, err){
                        if(err)  reject(err);
                        item._id = data._id;
                        resolve(item);
                    });
                });
            });
}

您可以使用减少，而不是映射来实现：

stats.reduce(
  (chain, item) =>
    // append the promise creating function to the chain
    chain.then(() => playersApi.getOrAddPlayer(item, clubInfo, year)),
  // start the promise chain from a resolved promise
  Promise.resolve()
).then(() => 
  // all finished, one after the other
);

示范：

const timeoutPromise = x => {
  console.log(`starting ${x}`);
  return new Promise(resolve => setTimeout(() => {
    console.log(`resolving ${x}`);
    resolve(x);
  }, Math.random() * 2000));
};

[1, 2, 3].reduce(
  (chain, item) => chain.then(() => timeoutPromise(item)),
  Promise.resolve()
).then(() =>
  console.log('all finished, one after the other')
);