Mailgun subscribers for a static website.

package.json

{
  "name": "nodelist",
  "version": "1.0.0",
  "description": "Mailing lists for DevPy.me",
  "main": "main.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Robert Washbourne",
  "license": "ISC",
  "dependencies": {
    "body-parser": "^1.15.2",
    "express": "^4.14.0",
    "mailgun-js": "^0.7.11",
    "validator": "^5.4.0"
  }
}

server.js

// NODEJS SERVER
var mailgun = require('mailgun-js')({apiKey: "MyAPIkey", domain: "devpy.me"});
var mlist = mailgun.lists('testlist@devpy.me');
var express = require('express');  
var bodyParser = require('body-parser');  
var validator = require('validator');
var app = express();

app.use(bodyParser.urlencoded({ extended: false }));  
app.use(bodyParser.json());  
app.use(function(req, res, next) {  
    res.header("Access-Control-Allow-Origin", "*");
    res.header("Access-Control-Allow-Credentials", "true");
    res.header("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
    res.header("Access-Control-Allow-Headers", "Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers");
    next();
});

app.post('/subscribe', function (req, res) {  
    var email = req.body.email;
    if(!email || !validator.isEmail(email)) return res.json({success: false, error: "That's not a valid email."});
    mlist.members().create({subscribed: true, address: email}, function (err, data) {
        if(data.message.indexOf("Address already exists") > -1) return res.json({success: false, error: "You're already subscribed. Thanks!"});
        res.json({success: true});
    });
});

app.listen(process.env.PORT);  
console.log("listening");

subscribe.html

<form onsubmit="event.preventDefault(); doSub();">
<fieldset>
  <legend>Subscribe</legend>
  <div>
    <input id="email" placeholder="Your Email Address" type="email" name="Email_Adress" value="" id="Email_Adress" autofocus required>
    <input class="button" type="submit" value="Subscribe">
  </div>
  <div id="subres"></div>
</fieldset>
</form>

<script>
function post(path, params) {
    var http = new XMLHttpRequest();
    var url = path;
    http.open("POST", url, true);
    http.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
    http.onreadystatechange = function() {
        if (http.readyState == 4 && http.status == 200) {
            var res = JSON.parse(http.responseText);
            var subres = document.getElementById("subres");
            if (res["success"] === true) {
                subres.innerHTML = "You are now subscribed.";
                ga('send', 'event', 'Subscribe', 'subscribe', 'Page');
            } else {
                subres.innerHTML = res["error"];
            }
        }
    }
    http.send(params);
}

function doSub() {
    var subres = document.getElementById("subres");
    subres.innerHTML = "one moment please...";
    var em = document.getElementById("email").value;
    post('https://changethisurl/subscribe', "email=" + em);
}
</script>