Using the Analytics.js Querystring API

Analytics.js can trigger Track and Identify events based on the URL query string. You can use this when tracking email click-throughs, social media clicks, and digital advertising.

Here are the optional query parameters to use:

Parameter Description Triggers
ajs_uid The userId to pass to an Identify call. This triggers an Identify call.
ajs_event The event name to pass to a Track call. This triggers a Track call.
ajs_aid The anonymousId to set for the user. This function returns the current anonymousId. When a value is passed, this function sets an anonymousId value.
ajs_prop_<property> A property to pass to the Track call. This won’t implicitly trigger an event and is dependent on you also passing ajs_event. This property is included in the resulting Track call.
ajs_trait_<trait> A trait to pass to the Identify call. This won’t implicitly trigger any call and is dependent on you also passing ajs_uid. This trait is included in the resulting Identify call.

For example, this URL:

would create the following events on the page.

analytics.identify('123456789abcd', { name: 'Karl Jr.' });
analytics.track('Clicked Email', { 'emailCampaign': 'First Touch' });

Each trigger parameter is optional. You can pass up to one of each trigger parameter as shown in the example above.

How can I control query string processing?

The useQueryString option allows you to control the behavior of the query parameters. For example, you can entirely disable query string processing by setting useQueryString to false:

analytics.load('<WRITE_KEY>', {
  useQueryString: false

You can also keep query string processing on, but enforce validation rules. For example:

analytics.load('<WRITE_KEY>', {
  useQueryString: {
    // set a pattern for anonymous id 
    aid: /([A-Z]{10})/,
    // set a pattern for user id
    uid: /([A-Z]{6})/

 The useQueryString option is only available when you load analytics.js through the NPM package.

This page was last modified: 31 May 2023

Get started with Segment

Segment is the easiest way to integrate your websites & mobile apps data to over 300 analytics and growth tools.
Create free account