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Snowplow JavaScript Tracker 2.5.0 released

We are excited to announce the release of version 2.5.0 of the Snowplow JavaScript Tracker! Among other things, this release adds new IDs for sessions and pageviews, making rich in-page and in-session analytics easier.

Read on for more information:

  1. The session ID
  2. The page view ID
  3. Context-generating functions
  4. New Grunt task
  5. Breaking change to trackPageView
  6. Breaking change to session cookie timeouts
  7. Upgrading
  8. Documentation and help

1. The session ID

In April, Snowplow Release 63 Red-Cheeked Cordon-Bleu added a “domain_sessionid” field to the enriched event model. This JavaScript Tracker release populates this field with a version 4 UUID that is unique to a given session. This ID is stored in the Snowplow ID cookie (which contains other persistent data, including the user ID). The ID is regenerated whenever the user is away from the domain for over 30 minutes (the time taken for the session cookie to expire). This ID is attached to every event.

If cookies are disabled, the session ID will be stored in memory rather than in a cookie. It will be regenerated after 30 minutes.

This release also changes how the JavaScript Tracker measures the visit count (which corresponds to the “domain_sessionidx” field in atomic.events) when cookies are disabled. Previously, every event sent would have visit count equal to 1. Now the Tracker keeps the visit count in memory and increments it when the user is inactive on the page for 30 minutes. Note that the visit count will still reset once the user reloads or leaves the page.

2. The page view ID

To make it easier to aggregate all events from a particular page load into single rows, we have added the new optional web_page context. This context has a single “id” field, containing a unique version 4 UUID for the page view. The UUID is generated on page load and the context is attached to all events fired on the page.

To enable this context, add “webPage” to the “contexts” field of the tracker construction argmap:

window.snowplow('newTracker', 'cf', 'd3rkrsqld9gmqf.cloudfront.net', { appId: 'CFe23a', platform: 'web', contexts: { performanceTiming: true, ... // Page view UUIDs enabled here webPage: true } <span class="p">});

3. Context-generating functions

When you add contexts to a page view, those contexts automatically get added to all subsequent page pings. But what if you want the contexts to update depending on new information?

It is now possible to pass a context-generating function to trackPageView. This function should return a (possibly empty) array of custom contexts. For example:

// Turn on page pings every 10 seconds window.snowplow('enableActivityTracking', 10, 10<span class="p">); window.snowplow( 'trackPageView', // no custom title null, // The usual array of static contexts [{ schema: 'iglu:com.acme/static_context/jsonschema/1-0-0', data: { staticValue: new Date().toString() } }], // Function which returns an array of custom contexts // Gets called once per page view / page ping function() { return [{ schema: 'iglu:com.acme/dynamic_context/jsonschema/1-0-0', data: { dynamicValue: new Date().toString() } <span class="p">}]; } <span class="p">);

Once the above code is executed, the initial page view and all page pings will have two contexts attached. The first, a static context which contains the datetime from the call to trackPageView, will be the same for all events. The second, a dynamic context, will be re-computed for every event, and will have a different datetime in each case.

4. New Grunt task

To speed up development, we have added a Grunt task which builds the tracker skipping the steps of building the custom lodash.js library and minification. You can invoke it from the command line in the root directory like this:

grunt quick

5. Breaking change to trackPageView

The previous version of the tracker deprecated the “performanceTiming” argument to the trackPageView function. This release removes it completely:

// Old // window.snowplow('trackPageView', customTitleString, performanceTimingBoolean, contextsArray); // New window.snowplow('trackPageView', customTitleString, contextsArray, contextGeneratingFunction<span class="p">);

6. Breaking change to session cookie timeouts

Using the setSessionCookieTimeout method is no longer effective. This is because the cookie is set as soon as the tracker is created, before the method gets a chance to be called. Instead, you can add a sessionCookieTimeout field to the tracker’s construction argmap:

window.snowplow('newTracker', 'cf', 'd3rkrsqld9gmqf.cloudfront.net', { appId: 'CFe23a', platform: 'web', sessionCookieTimeout: 3600, // one hour contexts: { performanceTiming: true, webPage: true } <span class="p">});

7. Upgrading

The upgraded minified tracker is available here:


Make sure to update your tracking code to reflect the two breaking changes highlighted above.

8. Documentation and help

Check out the JavaScript Tracker’s documentation:

The v2.5.0 release page on GitHub has the full list of changes made in this version.

Finally, if you run into any issues or have any questions, please raise an issue or get in touch with us via the usual channels.

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