Why doesn't my async function return any result?

Question

I wrote this small program to fetch data. This however is done async. Since I nonetheless need to use the function holeVertreter(kzl) as a function in another module, I'd like to get a return value which I can eventually pass on. Excuse my spaghetti code (I usually prettify the code when I am done with my task ...).

Credentials are stored in a file and are therefore not found in this file. I'd like to end up with "vertreter" as a return value.

Thank you in advance.

const node = require("deasync");
const DSB = require('dsbapi');
const tabletojson = require('tabletojson');
const https = require('https');
const cred = require("./vertrCred");

const dsb = new DSB(cred["dsb"]["user"], cred["dsb"]["passw"]); //Sanitized - no Credentials here

//Stackoverflow 2332811
String.prototype.capitalize = function(lower) {
    return (lower ? this.toLowerCase() : this).replace(/(?:^|\s)\S/g, function(a) { return a.toUpperCase(); });
};

function holePlan(kuerzel) {

dsb.fetch()
    .then(data => {
        const timetables = DSB.findMethodInData('timetable', data);
        const tiles = DSB.findMethodInData('tiles', data);

        var tilesStr = JSON.stringify(tiles["data"][0]["url"]);
        var url = JSON.parse(tilesStr);
        https.get(url, (resp) => {
        let data = '';
            resp.on('data', (chunk) => {
            data += chunk;
                });
            resp.on('end',() => {

            var tableasjson = tabletojson.convert(data);
            var erstetab = tableasjson[0];
            var zweitetab = tableasjson[1];
            var drittetab = tableasjson[2];
            var viertetab = tableasjson[3];
            var fuenftetab = tableasjson[4];
            var sechstetab = tableasjson[5];
            var siebtetab = tableasjson[6];
            var achtetab = tableasjson[7];
            if (typeof kuerzel === "undefined")
            {
                var regenechse = '(Aaa|Aaa[A-Za-z?]|[A-Za-z?]Aaa)';

                }
            else {
                var name = kuerzel.capitalize(true);
                var regenechse = '('+name+'|'+name+'[A-Za-z?]|[A-Za-z?]'+name+')';
            }
            const regex = new RegExp(regenechse,'g');
            var sammel = Object.assign(drittetab,fuenftetab);
            var z= 0;
            var vertreter = {}
            var y = JSON.parse(JSON.stringify(sammel));
            for (i=0;i<y.length;i++)    {
            if (typeof y[i].Vertreter =='undefined') {
            }
            else {
                if(y[i].Vertreter.match(regex))
                {
                    z += 1;

                    vertreter[z] = y[i];
                }
         }
        }
            if (z == 0) {
//              console.log("Es gibt nichts zu vertreten");
                }
            else {
                //console.log("Es werden "+z+" Stunden vertreten");
                return (vertreter);
            }   ;
                });

        })
        })
    .catch(e => {
        // An error occurred :(
        console.log(e);
    });
}

//Stackoverflow
function warte(promise) {
    var done = 0;
    var result = null;
    promise.then(
    function (value) {
        done = 1;
        result = value;
        return (value);
    },
    function (reason) {
        done = 1;
        throw reason;
        }
    );

    while (!done)
        node.runLoopOnce();
    return (result);
    }

function holeVertretung(kzl) {
    var aufgabe = new Promise((resolve,reject) => {
        setTimeout(resolve,1000,holePlan(kzl));
        });
    var ergebnis = warte(aufgabe);
    if (typeof ergebnis === "undefined")    {
        console.log("Mist");
    }
    else {
    console.log(ergebnis);
    }
    return ergebnis;
    }

holeVertretung("Aaa");

Answer 1

That's not the right way to work with promises. If you do such infinite loop, it beats the whole purpose of using promises. Instead, return value from the promise, and use async-await like this:

function warte(promise) {
  var done = 0;
  var result = null;
  return promise.then(
    ...
}

async function holeVertretung(kzl) {
  var aufgabe = new Promise((resolve, reject) => {
    setTimeout(resolve, 1000, holePlan(kzl));
  });
  var ergebnis = await warte(aufgabe);
  ...

If async-await does not work for some reason, use then clause:

warte(aufgabe).then(value => {
  var ergebnis = value;
});