app.js

const parser = require("body-parser");
const express = require("express");
const request = require("request");
const https = require("https");

const app = express();

app.use(express.static("public"));
app.use(parser.urlencoded({ extended: true }));

app.get("/", function(req, res) {
    res.sendFile(__dirname + "/signup.html")
});

app.post("/", function(req, res) {
    const fname = req.body.fname;
    const lname = req.body.lname;
    const email = req.body.email;

    var data = {
        members: [{
            email_address: email,
            status: "subscribed",
            merge_fields: {
                FNAME: fname,
                LNAME: lname
            }
        }]
    }

    var jsonData = JSON.stringify(data);

    const url = "https://us10.api.mailchimp.com/3.0/lists/94bc2f7a88";

    const options = {
        method: "POST",
        auth: "rahul:861c51a95854865cf96765ff763a5595-us10"
    }

    const request = https.request(url, options, function(response) {

        if (response.statusCode === 200) {
            res.sendfile(__dirname + "/success.html");
        } else {
            res.sendfile(__dirname + "/failure.html");
        }

        response.on("data", function(data) {
            console.log(JSON.parse(data));
        })

    });

    request.write(jsonData);
    request.end();
});

app.listen(3000, function() {
    console.log("Server Ready");
});