Testing Firebase Auth REST API

get_id_token.js

const https = require('https');

const API_KEY = "YOUR_API_KEY";
const email = "YOUR_EMAIL@EXAMPLE.COM";
const pass = "YOUR_SECRET_PASSWORD";
const signInUrl = `https://identitytoolkit.googleapis.com/v1/accounts:signInWithPassword?key=${API_KEY}`

// login data; this will be sent on the POST request
// NOTE: the parameter 'returnSecureToken' must be true to get the idToken
const postData = {
    email: email,
    password: pass,
    returnSecureToken: true
};

// request parameter
const options = {
    hostname: "identitytoolkit.googleapis.com",
    port: 443,
    path: `/v1/accounts:signInWithPassword?key=${API_KEY}`,
    method: "POST",
    headers: {
        "Content-Type": "application/json"
    }
};

// sending the request
let req = https.request(options, res => {
    console.log();

    // this is the response from the request; this is done 'asynchronously'
    res.on("data", data => {
        responseData = JSON.parse(data.toString());
        // if the login works, this is the idToken;
        // you can echo the full 'responseData' to see what is returned
        console.log(responseData.idToken);
    });

});

req.on("error", err => {
    console.error(err.message);
});

// writing the POST data
req.write(Buffer.from(JSON.stringify(postData), 'utf8'), err => {
    if (err) {
        console.error(err.message);
    }
});

// finishing the request
req.end();