Sitecore Experience Editor 8.2-2 compatible warmup PhantomJS script to be triggered using Powershell (for example as Azure WebJob). Based on PhantomJS because it's already available on Sitecore 8 environments. Some paths are currently still hardcoded for webapps

ee-warmup.js

var page = new WebPage(), testindex = 0, loadInProgress = false;
var args = require('system').args;
var host = args[1];
var username = args[2];
var password = args[3];
var pageEditorUrl = args[4];
var token;
var system = require('system');
phantom.cookiesEnabled = true;
phantom.javascriptEnabled = true;
page.settings.javascriptEnabled = true;
page.settings.loadImages = false;

console.log("Launching Experience Editor Warmup script:");
console.log("DIAG User:" + username);
console.log("DIAG Host:" + host);
console.log("DIAG PageEditorUrl:" + pageEditorUrl);

steps = [
    function () {
        page.open(host + "/sitecore/login", function (status) {
            if (status == 'fail')
            {
                console.log('Sitecore login call failed')
                phantom.exit(1);
            }
        });
    },
    function () {
        var auth = { user: username, pass: password };
        page.evaluate(function (auth) {
            var arr = document.getElementsByClassName("form-signin");
            var i;

            for (i = 0; i < arr.length; i++) {
                if (arr[i].getAttribute('method') == "post") {

                    arr[i].elements["UserName"].value = auth.user;
                    arr[i].elements["Password"].value = auth.pass;
                    return;
                }
            }
        }, auth);
    },
    function () {
        page.evaluate(function () {
            console.log("Submitting login");
            var submitbtn = document.querySelectorAll("input[type=submit]")

            if (!submitbtn[0])
            {
                console.log('Sitecore login button not found')
                phantom.exit(1);
            }

            submitbtn[0].click();
        });
    },
    function () {
        page.evaluate(function () {
            
        });
    },
    function () {
        var url = host.concat(pageEditorUrl);
        page.open(url, function (status) {

        });
    },
    function () {
        token = page.evaluate(function () {
            console.log(document.querySelectorAll('html')[0].outerHTML);
            var verificationToken = document.getElementsByName("__RequestVerificationToken");
            return verificationToken[0];
        });
    },
    function () {
        var logoutUrl = host.concat('/sitecore/shell/api/sitecore/Authentication/Logout?sc_database=master');
        console.log("Logging out");
        var postData = "__RequestVerificationToken=".concat(token.value);
        page.open(logoutUrl, 'POST', postData, function (status) {
        });
    },
    function () {
        var url = host.concat('/sitecore/login');
        page.open(url, function (status) {

        });
    },
    function () {
        page.evaluate(function () {
           console.log(document.querySelectorAll('html')[0].outerHTML);
           console.log("Logged out");
        });
    }
];

interval = setInterval(executeRequestsStepByStep, 150);

function executeRequestsStepByStep() {
    if (loadInProgress == false && typeof steps[testindex] == "function") {
        steps[testindex]();
        testindex++;
    }
    if (typeof steps[testindex] != "function") {
        console.log("test complete!");
        phantom.exit();
    }
}

page.onLoadStarted = function () {
    loadInProgress = true;
    console.log('Loading started');
};
page.onLoadFinished = function () {
    loadInProgress = false;
    console.log('Loading finished');
};
page.onConsoleMessage = function (msg) {
    console.log(msg);
};

experience-editor.ps1

$CurrentDir = Split-Path -Parent $MyInvocation.MyCommand.Path

[xml]$ConfigFile = Get-Content $CurrentDir"\experience-editor.xml"

$settings = @{
    Username = $ConfigFile.Settings.Username
    Password = $ConfigFile.Settings.Password
    ExperienceEditorUrl = $ConfigFile.Settings.ExperienceEditorUrl
    Hostname = $ConfigFile.Settings.Hostname
    }

D:\home\site\wwwroot\App_Data\tools\phantomjs\phantomjs --ssl-protocol=any --ignore-ssl-errors=yes D:\home\site\wwwroot\script\ee-warmup.js $settings.Hostname $settings.Username $settings.Password $settings.ExperienceEditorUrl

experience-editor.xml

<?xml version="1.0" encoding="utf-8" ?>
<Settings>
  <Hostname>https://mywebsite-cm.azurewebsites.net</Hostname>
  <ExperienceEditorUrl>?sc_mode=edit&amp;sc_itemid=%7bB4423450-C432-485B-A709-64BA1168A9D4%7d&amp;sc_version=10&amp;sc_lang=en&amp;sc_site=MySite</ExperienceEditorUrl>
  <Username>EeWarmupUser</Username>
  <Password>SuperSecretPW</Password>
</Settings>