app.js

var Crawler = require("simplecrawler");
var querystring = require('querystring');

var myCrawler = new Crawler("www.geocaching.com", "/login/");
myCrawler.initialProtocol = "https";
myCrawler.acceptCookies = true;
myCrawler.on("addcookie", function (cookie) {
    console.log("Cookie");
});

myCrawler.on("crawlstart", function () {
    console.log("Crawler start")
});

myCrawler.on("fetchstart", function (queueItem, requestOptions) {
    if (requestOptions.host + requestOptions.path == "www.geocaching.com/login/"){
        requestOptions.method = 'POST';
        requestOptions.headers['User-Agent'] = "Mozilla/5.0 (Windows NT 6.a; WOW64; rv:33.0) Gecko/20100101 Firefox/33.0";
        requestOptions.headers['Content-Type'] = 'application/x-www-form-urlencoded';
        var form = {
            "_EVENTTARGET": "",
            "_EVENTARGUMENT": "",
            "_VIEWSTATE": "",
            "ctl00$ContentBody$tbUsername": "user",
            "ctl00$ContentBody$tbPassword":"pass",
            "ctl00$ContentBody$btnSignIn": "Sign+In"
        };
        var formData = querystring.stringify(form);
        var contentLength = formData.length;
        requestOptions.headers['Content-Lenght'] = contentLength;
        requestOptions.body = formData;
        //console.log(requestOptions);
    }
});