Simple Sparkpost api usage

sparkpost.js

console.log('Loading function');
var http = require("https");
var fs = require('fs');

var options = {
    "method": "POST",
    "hostname": "api.sparkpost.com",
    "path": "/api/v1/transmissions?num_rcpt_errors=3",
    "headers": {
        "Content-Type": "application/json",
        "Accept": "application/json",
        "Authorization": "<api_key>",
        "cache-control": "no-cache"
    }
};

async function iterate() {
    let emails = ['[email protected]', '[email protected]']
    let recipients = [];

    for (var i = 0; i < emails.length; i++) {
        let email = emails[i];
        recipients.push({
            address: email
        });
        let req = http.request(options, function(res) {
            var chunks = [];

            res.on("data", function(chunk) {
                chunks.push(chunk);
            });

            res.on("end", function() {
                var body = Buffer.concat(chunks);
                console.log(body.toString());
            });
        });

        req.write(JSON.stringify({
            campaign_id: 'some_campaign',
            recipients: recipients,
            content: {
                template_id: "<template_id>"
            }
        }));
        req.end();
    }
}
iterate();