I am declaring a function, but it is non callable, why? - node.js

Question

I am declaring a function using Node.js, but it is being non callable.
I do not understand what is wrong since I declared it as the same way as the other functions and this is the only one that is being non callable.
My code:
const mysql = require('mysql');
const mainKey = '';
const con = mysql.createConnection({
host: "localhost",
user: "root",
database: "hotels"
});
function getUsers() {
return new Promise(function(resolve, reject) {
var users = new Array();
const sql = "SELECT * FROM users";
con.query(sql, function(err, result, fields) {
if(err) throw err;
users = [];
for(var i = 0; i<result.length; i++) {
users.push([result[i].id, result[i].user, result[i].password]);
}
resolve(users);
});
});
}
function regUser(user, password, key) { //this function is non callable
return new Promise(function(resolve, reject){
console.log(test)
});
}
function getHotelNames(idUser) {
return new Promise(function(resolve, reject){
var hotelNames = new Array();
const sql = "SELECT * FROM hotels WHERE user=" + idUser;
con.query(sql, function (err, result, fields) {
if (err) throw err;
hotelNames = [];
for(var i=0; i<result.length; i++) {
hotelNames.push(escape(result[i].name));
}
resolve(hotelNames);
});
})
}
function getURLs() {
return new Promise(function(resolve, reject){
var urlsHotels = new Array();
const sql = "SELECT * FROM hotels";
con.query(sql, function (err, result) {
if (err) throw err;
urlsHotels = [];
for(var i=0; i<result.length; i++) {
urlsHotels.push(result[i].url);
}
resolve(urlsHotels);
});
})
}
function insertValues(hotelNames, url, name, idUser) {
return new Promise(function(resolve, reject){
const id = hotelNames.length+1
const sql = "INSERT INTO hotels (id, name, url, user) VALUES (" + id + ", '" + name + "', '" + url + "', " + idUser +")";
con.query(sql, function (err, result) {
if (err) resolve(['errorNewHotel']); //throw err;
resolve(['NewHotel'])
});
})
}
function deleteValues(name) {
return new Promise(function(resolve, reject){
const sql = "DELETE FROM hotels WHERE name = '" + name + "'";
console.log(sql)
con.query(sql, function (err, result) {
if (err) resolve(['errorDeletingHotel']); //throw err;
resolve(['deletedHotel'])
});
})
}
const funcGetUsers = async ()=> {
const users = await getUsers();
return users;
}
const funcRegisterUser = async (user, password, key)=> {
const regUser = await regUser(user, password, key); //I am calling the function here
return regUser;
}
const funcGetHotelNames = async (idUser)=> {
const hotelNames = await getHotelNames(idUser);
return hotelNames;
}
const funcGetURLs = async ()=> {
const urls = await getURLs();
return urls;
}
const funcInsertValues = async(hotelNames, url, name, idUser)=> {
const message = await insertValues(hotelNames, url, name, idUser);
return message;
}
const funcDeleteValues = async(name)=> {
const message = await deleteValues(name);
return message;
}
module.exports.funcGetUsers = funcGetUsers;
module.exports.funcRegisterUser = funcRegisterUser;
module.exports.funcGetHotelNames = funcGetHotelNames;
module.exports.funcGetURLs = funcGetURLs;
module.exports.funcInsertValues = funcInsertValues;
module.exports.funcDeleteValues = funcDeleteValues;
Even my code editor, Visual Studio Code says it is never read
That is what I get when I try to run function:
I do not think the issue comes from the main file (server.js), so I have tried to copy all the code in a new file and Visual Studio was still saying that it is never read while the other functions were fine.
What am I doing wrong? I do not get it.
Thank you in advance.

Answer 1

The real Javascript error is:
ReferenceError: regUser is not defined
In
const funcRegisterUser = async (user, password, key)=> {
const regUser = await regUser(user, password, key); //I am calling the function here
return regUser;
}
You're trying to assign to a variable named regUser while also calling a function named regUser. But, because you declare a variable named regUser inside that function, any references to a variable named regUser inside that function will refer to that regUser variable. So your await regUser(...) is trying to await the variable which has not been assigned to yet - it's in the temporal dead zone.
Just use a different variable name, and you'll avoid the name collision:
const funcRegisterUser = async (user, password, key)=> {
const result = await regUser(user, password, key);
return result;
}
Or, just return the Promise itself, no need to await something you immediately return:
const funcRegisterUser = (user, password, key) => (
regUser(user, password, key)
);
Or, even better, since funcRegisterUser is just calling regUser, maybe leave out funcRegisterUser entirely, and just export regUser:
module.exports.funcRegisterUser = regUser;

Answer 2

The problem is not in the function, but how you call it.
const regUser = await regUser(user, password, key);
This line will create a new constant regUser as undefined, then try to invoke it as a function. Your function is shadowed in outer scope, and thus inaccessible. The solution is simple: change the name of your constant.