Promise is undefined in procedural code in nodejs - node.js

Question

I'm very new to async languages like nodejs, I'm trying to write a web scraper that will visit a link, download a code, extract with regex, THEN visit another link using that code. I'm aware I could use callbacks, but I expect to have to go 8-9 levels deep, I think promises is the way to go (is there a better way?)
var promise = require("promise");
var request = require("request");
login();
function get_login_code()
{
request.get("someurl.com", function (error, response, body)
{
// just for example
body = 'TOKEN" value="hello world"';
var login_code = body.match(/.TOKEN" value="([^"]+)../i);
return login_code
});
}
function login()
{
var login_promise = promise.resolve(get_login_code());
console.log(login_promise);
}
I've tried a bunch of combinations of messing around with promises, but I either always get undefined or a promise which doesn't have a value. I don't want to nest promise functions inside promises because that's exactly the same thing as callback hell. Can someone tell me what I'm doing wrong, I really want this code to be procedural and not 8 callbacks. In the ideal world promise.resolve just waits until get_login_code() returns the actual code, not undefined.
Output:
Promise { _45: 0, _81: 1, _65: undefined, _54: null }
Desired Output:
hello world

Answer 1

What your code do:
calls get_login_code that returns nothing (i.e. undefined)
inside of login function you create a new promise that is immediately resolved to the result of get_login_code, i.e. undefined.
Thus, you do not use login_code at all.
To make it work, you should make get_login_code to return a promise that will be resolved to login_code. Consider you use promise npm module, the code may look like:
// uppercased, it's a constructor
var Promise = require("promise");
var request = require("request");
login();
function get_login_code()
{
return new Promise(function (resolve, reject) {
request.get("someurl.com", function (error, response, body) {
if (err) {
reject(err);
return;
}
// just for example
body = 'TOKEN" value="hello world"';
var login_code = body.match(/.TOKEN" value="([^"]+)../i);
resolve(login_code);
});
});
}
function login()
{
// return a new promise to use in subsequent operations
return get_login_code()
.then(function(login_code) {
console.log(login_code);
});
}

Answer 2

You should create new promise in the function to handle reject and resolve not by handling resolve to the function itself. Use then to get the response value from promise. I guess this should work.
var promise = require("promise");
var request = require("request");
function get_login_code()
{
var promise = new Promise(function(resolve, reject) {
request.get("someurl.com", function (error, response, body)
{
if (error) {
reject(error);
} else {
// just for example
body = 'TOKEN" value="hello world"';
var login_code = body.match(/.TOKEN" value="([^"]+)../i);
resolve(login_code);
}
});
});
}
get_login_code()
.then(function (code) {
console.log(code);
});