NodeJS Making a for loop asynchronous

Question

I'm having a bit of trouble with a NodeJS program I have.

So the way my for loop is supposed to function is, it should iterate through the indices from my SQL Database and in each run of the for loop, it's supposed to make a call to another function which makes a GET request.

What it actually does though is it iterates through all of my indices and THEN makes every GET request all at once/very fast, which ends up getting me limited from making anymore API calls. I tried using setTimeout but that doesn't work since it just iterates to the next index and the values end up being undefined.

Also tried a callback but it didn't change anything. I tried looking into async but can't really get my head around what I'm supposed to be doing. Also just a note, nothing is actually being returned. In my other function I'm just updating my SQL DB. I just need the for loop to make an API call per run and only continue after it's complete.

    function callGet() {

    var mysql = require('mysql');
    var con = mysql.createConnection({
        host: "localhost",
        user: "USERNAME",
        password: "PASSWORD",
        database: "sys"
    });

    con.query("SELECT nameAlone FROM testDB", function(err, result, fields) {

       var i;

        for(i = 0; i < result.length; i++){

        var name = result[i].nameAlone;

        var options = {
            method: 'GET',
            url: 'site.com',
            qs: {
                key: 'MYKEY',
                page_size: 10,
                intent: 0,
                itemName: name
            },
            headers: {
                'postman-token': postman-token,
                'cache-control': 'no-cache'
            }
        };  
        getListing(options,result, i);                  //Only being called after the for loop iterates through all of result.length
}
    });
}

An example of what's happening is this, let's say the for loop iterates from 0-2 and each run calls a function that prints out a name. Instead of

index:0, name:Chris, index:1, name:Tony, index:2, name:John

It'll print out:

index:0, index:1, index:2, name:Chris, name:Tony, name:John

Thanks in advance for any help.

Edit: I already attempted all of the answers that applied to my issue in the duplicate question suggested. Trying to mess around with one of the answers there but not too sure if it'll work.

Edit2: All the solutions there didn't work.

Edit3(solution): In case anyone wants a very simple solution,I found this package which was very easy to setup: https://github.com/nathan818fr/async-loop

All I had to do was create an array with my indices and setup the asyncLoop as following:

asyncLoop(indices, function (item, next)
{
    var name = result[item].nameAlone;
    var options = {
        method: 'GET',
        url: 'site.com',
        qs: {
            key: 'MYKEY',
            page_size: 10,
            intent: 0,
            itemName: name
        },
        headers: {
            'postman-token': postman-token,
            'cache-control': 'no-cache'
        }
    };  

    getListing(options,result, item);
    next();
}, function ()
{
    console.log('Finished!');
});

Answer 1

You can use my 'ploop' function with promises. ploop basically takes a function that returns a promise, any arguments needed by the function and a function that decides whether ploop is done or not. You do not fill in the 4th argument. Below is an example using ploop to draw random numbers until it finds the number 4:

// Function that returns a promise
var searchForNumber = function(number) {
    return new Promise(function(resolve, reject) {
      setTimeout(function() {
        var min = 1;
        var max = 10;
        var val = Math.floor(Math.random()*(max-min+1)+min);

        console.log('Value is: ' + val.toString());        

        return resolve(val);        
      }, 1000);
    });
};

// fn     : function that should return a promise.
// args   : the arguments that should be passed to fn.
// donefn : function that should check the result of the promise
//    and return true to indicate whether ploop should stop or not.
// promise: A promise value that is used internally by ploop and should never 
//    be passed in by the caller of ploop.
var ploop = function(fn, args, donefn, promise) {
    return (promise || Promise.resolve(true))    
      .then(function() {
          return(fn.apply(null, args));
      })
      .then(function(result) {
        var finished = donefn(result);
        if(finished === true){
           return result;
        } else {
          return ploop(fn, args, donefn, promise);
        }
    });
};

var searchFor = 4;

var donefn = function(result) {
  return result == searchFor;
};

console.log('Searching for: ' + searchFor);
ploop(searchForNumber, [searchFor], donefn)
  .then(function(val) {
    console.log('Finally found! ' + val.toString());  
    process.exit(0);
  })
  .catch(function(err) {
    process.exit(1);
  });

Everything but the ploop function itself is sample code. Here is the demo:

http://jsbin.com/woxetos/edit?js,console