This code will refresh all users on your webpage upon deployment of a timestamp.json file to S3. We used this to deploy hotfixes on election night for elections.npr.org. It requires Fabric (a Python library for running tasks on the command line) and jquery-cookie.js, but could easily be refactored to not.

deploy_timestamp.py

#!/usr/bin/env python

"""
On the server (or locally), deploy a timestamp to S3
if we need to refresh all browsers 
currently connected to our page
"""

from datetime import datetime
import json

from fabric.api import local, task

@task
def reset_browsers():
    """
    Create a timestampped JSON file so the client will reset their page.
    """
    payload = {}

    # get current time and convert to epoch time
    now = datetime.now().strftime('%s')
    
    # set everything you want in the json file
    payload['timestamp'] = now

    with open('www/live-data/timestamp.json', 'w') as f:
        json.dump(now, f)

    deploy_json('www/live-data/timestamp.json', 'live-data/timestamp.json')

def deploy_json(src, dst):
    """
    Deploy to S3. Note the cache headers.
    """
    bucket = 'elections.npr.org'
    region = 'us-west-2'
    
    sync = 'aws s3 cp %s %s --acl "public-read" --cache-control "max-age=5 no-cache no-store must-revalidate" --region "%s"'

    local(sync % (src, 's3://%s/%s' % (%s, dst), bucket_region))

LICENSE

The MIT License (MIT)
Copyright (c) 2014 NPR

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

reload.js

/*
* On the client, poll for the timestamp file and check to see if a new timestamp has been deployed.
* If so, refresh the client.
*/

var reloadTimestamp = null;

var getTimestamp = function() {
    // get the timestamp on page load
    if (reloadTimestamp == null) {
        checkTimestamp();
    }
    
    // continually check the timestamp every three minutes
    setInterval(checkTimestamp, 180000);
}

var checkTimestamp = function() {
    $.ajax({
        'url': '/live-data/timestamp.json',
        // bust the browser cache
        'cache': false,
        'success': function(data) {
            var newTime = data['timestamp'];
            
            // if we haven't set a timestamp yet, set it
            if (reloadTimestamp == null) {
                reloadTimestamp = newTime;
            }
            
            // if the initial timestamp doesn't match the new one, refresh the page
            if (reloadTimestamp != newTime) {
                // set a cookie in case we need to do special things on this reload
                $.cookie('reload', true);
                
                window.location.reload(true);
            }
        }
    });
}

$(document).ready(function)() {
    getTimestamp();
    
    // stuff you only want to happen if we forced a refresh, like skipping a welcome screen
    if ($.cookie('reload')) {
        // stuff
        
        $.removeCookie('reload');
    }
});

timestamp.json

{
    "timestamp": "1415214618"
}