Advanced Usage

This section covers the more advanced elements of the JavaScript Tracker.

📄️ Optional timestamp argument

Each track...() method supports an optional timestamp property; this allows you to manually override the timestamp attached to this event. The timestamp should be in milliseconds since the Unix epoch.

📄️ Tracker Callbacks

If you call snowplow with a function as the argument, the function will be executed when sp.js loads:

📄️ Getting the most out of performance timing

The domComplete, loadEventStart, and loadEventEnd metrics in the NavigationTiming API are set to 0 until after every script on the page has finished executing, including sp.js. This means that the corresponding fields in the PerformanceTiming reported by the tracker will be 0. To get around this limitation, you can wrap all Snowplow code in a setTimeout call:

📄️ Creating a white-label build

Every time the snowplow tracker loads on the page, a queue-like object GlobalSnowplowNamespace is initialised on the global window scope. This object is then used to queue commands before the tracker snippet (sp.js) has fully loaded.