Tracker Callbacks

caution

You are reading documentation for an outdated version. Here’s the latest one!

Documentation for latest release

The documentation listed here is for Version 2 of the JavaScript Tracker. Version 3 is now available and upgrading is recommended.

- Documentation for Version 3

- v2 to v3 Migration Guide

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

snowplow(function () {
  console.log("sp.js has loaded");
});

Or equivalently:

snowplow(function (x) {
  console.log(x);
}, "sp.js has loaded");

The callback you provide is executed as a method on the internal trackerDictionary object. This means that you can access the trackerDictionary using this.

// Configure a tracker instance named "cf"
snowplow('newTracker', 'sp', '{{COLLECTOR_URL}}', {
 appId: 'snowplowExampleApp'
});

// Access the tracker instance inside a callback
snowplow(function () {
 var sp = this.sp;
 var domainUserId = sp.getDomainUserId();
 console.log(domainUserId);
})

The callback function should not be a method:

// TypeError: Illegal invocation
snowplow(console.log, "sp.js has loaded");

will not work, because the value of this in the console.log function will be trackerDictionary rather than console.

You can get around this problem using Function.prototoype.bind as follows:

snowplow(console.log.bind(console), "sp.js has loaded");

For more on execution context in JavaScript, see the MDN page.

Methods which can be used from within a callback

getDomainUserId

The getDomainUserId method returns the user ID stored in the first-party cookie:

// Access the tracker instance inside a callback
snowplow(function () {
 var sp = this.sp;
 var domainUserId = sp.getDomainUserId();
 console.log(domainUserId);
})

getDomainUserInfo

The getDomainUserInfo method returns all the information stored in first-party cookie in an array:

// Access the tracker instance inside a callback
snowplow(function () {
 var sp = this.sp;
 var domainUserInfo = sp.getDomainUserInfo();
 console.log(domainUserInfo);
})

The domainUserInfo variable will contain an array with 7 elements:

1. A string set to '1' if this is the user's first session and '0' otherwise
2. The domain user ID
3. The timestamp at which the cookie was created
4. The number of times the user has visited the site
5. The timestamp for the current visit
6. The timestamp of the last visit
7. The session id

getUserId

The getUserId method returns the user ID which you configured using setUserId():

// Access the tracker instance inside a callback
snowplow(function () {
 var sp = this.sp;
 var userId = sp.getUserId();
 console.log(userId);
})

getCookieName

The getCookieName method returns the complete cookie name for the domain or session cookie:

// Access the tracker instance inside a callback
snowplow(function () {
 var sp = this.sp;
 var cookieName = sp.getCookieName('id');
 console.log(cookieName);
})

The argument corresponds to the basename of the cookie: 'id' for the domain cookie, 'ses' for the session cookie.

getPageViewId

The getPageViewId method returns the page view id:

// Access the tracker instance inside a callback
snowplow(function () {
 var sp = this.sp;
 var pageViewId = sp.getPageViewId();
 console.log(pageViewId);
})