Cookie transformation snippet

cookie_update.js

/**
 * Snippet to deal with two Snowplow cookies on the same page but with different paths.
 * First, load the contents of the local cookie and delete it.
 * Then load the contents of the root cookie.
 * Combine the two sets of information, for example by adding together the session counts.
 * Save the resulting information in the root cookie.
 * 
 * WARNING! This is experimental and untested and should not be run lightly!
 * It may not work if the cookies do not both exist or are not set on the expected domain.
 */

// The cookie creation and extraction function the JS Tracker uses
/*
* @version    0.3.1
* @date       2014-02-25
* @stability  2 - Unstable
* @author     Lauri Rooden <[email protected]>
* @license    MIT License
*/
this.cookie = function(name, value, ttl, path, domain, secure) {

	if (arguments.length > 1) {
		return document.cookie = name + "=" + escape(value) +
			(ttl ? "; expires=" + new Date(+new Date()+(ttl*1000)).toUTCString() : "") +
			(path   ? "; path=" + path : "") +
			(domain ? "; domain=" + domain : "") +
			(secure ? "; secure" : "")
	}

	return unescape((("; "+document.cookie).split("; "+name+"=")[1]||"").split(";")[0])
}

// Substitute your cookie name here - you can find it with `console.log('document.cookie');`
var snowplowCookieName = '_sp_id.4209';

// Substitute your root domain here
var myDomain = 'snowplowanalytics.com';

// Load the local cookie
var localCookie = cookie(snowplowCookieName).split('.');

if (localCookie) {

	// Delete the local cookie
	cookie(snowplowCookieName, 'anything', -1000);

	// Load the root cookie
	var rootCookie = cookie(snowplowCookieName).split('.');

	if (rootCookie) {

		cookie(snowplowCookieName, [

			// The domain user ID
			localCookie[0],

			// The time of the first visit
			Math.min(localCookie[1], rootCookie[1]),

			// Sum of visits from the two cookies
			localCookie[2] + rootCookie[2],

			// The time of the current visit
			Math.max(localCookie[3], rootCookie[3]),

			// Last visit
			Math.max(localCookie[4], rootCookie[4])
		].join('.'),

		// Expire in 2 years
		63072000,

		// The root path
		'/',

		// Domain of your choice
		myDomain);

	} else {

		cookie(snowplowCookieName, localCookie.join('.'),

		// Expire in 2 years
		63072000,

		// The root path
		'/',

		// Domain of your choice
		myDomain);
	}

}