Is the variable not being initialized outside of the function?

Question

Is the variable not being initialized outside of the function?

I'm really struggling with this async issue. I can't seem to get it to work because the summonerData array is not being set. I have a feeling it has something to do with async, but I'm not sure how to troubleshoot it.

var summonerName = req.params.playerName;
var summonerData = [];
var summonerIds = [];
var summonerGames = [];
redis.exists(summonerName, function(err, reply) {
    if (reply === 1) {
      console.log('Data Found for Summoner in Redis!: ' + summonerName);
      redis.hgetall(summonerName, function(err, object) {
        summonerData.push(object);
      });
    } else {
      console.log('Data not Found for Summoner: ' + summonerName);
      lolapi.Summoner.getByName(summonerName, function(error, summoner) {
        if (summoner) {
          console.log('Summoner was retrieved by API! and Saved to Redis!');
          redis.hmset(summonerName, summoner[summonerName]);
          summonerData.push(summoner[summonerName]);
        }
      });
    }
});
console.log(summonerData);

javascript

Answer 1

Answer №1

Implementing asynchronous functionality involves triggering a function to execute at a later time. By utilizing redis.exists, you are setting up the function to be called in the future, while the subsequent line, console.log(summonerData), executes before the callback is triggered.

To ensure the desired outcome, it is essential to place console.log(summonerData) inside the function itself.

Answer 2

Implementing asynchronous functionality involves triggering a function to execute at a later time. By utilizing redis.exists, you are setting up the function to be called in the future, while the subsequent line, console.log(summonerData), executes before the callback is triggered.

To ensure the desired outcome, it is essential to place console.log(summonerData) inside the function itself.

Answer 3

Answer №2

For optimal performance, it is recommended to utilize promises

var fetchSummonerInfo = function (summonerName) {
    return new Promise(function (resolve, reject) {
        var summonerData = [];
        var summonerIds = [];
        var summonerGames = [];
        redis.exists(summonerName, function (err, reply) {

            if (err) {
                return reject(err);
            }

            if (reply === 1) {
                console.log('Data Found for Summoner in Redis!: ' + summonerName);
                redis.hgetall(summonerName, function (err, object) {
                    if (err) {
                        return reject(err);
                    }
                    summonerData.push(object);
                    resolve(summonerData);
                });
            } else {
                console.log('Data not Found for Summoner: ' + summonerName);
                lolapi.Summoner.getByName(summonerName, function (error, summoner) {
                    if (error) {
                        return reject(error);
                    }
                    if (summoner) {
                        console.log('Summoner was retrieved by API! and Saved to Redis!');
                        redis.hmset(summonerName, summoner[summonerName]);
                        summonerData.push(summoner[summonerName]);
                    }
                    resolve(summonerData);
                });
            }
        });
    });
};


fetchSummonerInfo(req.params.playerName)
        .then(function (summonerData) {
                res.render(..., summonerData);
        });

Explore more about promises here:

Answer 4

For optimal performance, it is recommended to utilize promises

var fetchSummonerInfo = function (summonerName) {
    return new Promise(function (resolve, reject) {
        var summonerData = [];
        var summonerIds = [];
        var summonerGames = [];
        redis.exists(summonerName, function (err, reply) {

            if (err) {
                return reject(err);
            }

            if (reply === 1) {
                console.log('Data Found for Summoner in Redis!: ' + summonerName);
                redis.hgetall(summonerName, function (err, object) {
                    if (err) {
                        return reject(err);
                    }
                    summonerData.push(object);
                    resolve(summonerData);
                });
            } else {
                console.log('Data not Found for Summoner: ' + summonerName);
                lolapi.Summoner.getByName(summonerName, function (error, summoner) {
                    if (error) {
                        return reject(error);
                    }
                    if (summoner) {
                        console.log('Summoner was retrieved by API! and Saved to Redis!');
                        redis.hmset(summonerName, summoner[summonerName]);
                        summonerData.push(summoner[summonerName]);
                    }
                    resolve(summonerData);
                });
            }
        });
    });
};


fetchSummonerInfo(req.params.playerName)
        .then(function (summonerData) {
                res.render(..., summonerData);
        });

Explore more about promises here:

Is the variable not being initialized outside of the function?

Answer №1

Answer №2

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