Technical Aspects of the Attributes List in VWO

The Attributes List contains custom attributes that enable you to target a category of visitor/audience identified outside of VWO. All you need to do is, create a list with such attributes, upload it to VWO, and then use it as a targeting condition in your VWO campaigns.

The Attributes List primarily aims at targeting visitors/audiences who are not easily targeted by the targeting conditions available in VWO. To know more about what Attributes List is, what it can do for you, and how to use it in VWO, refer to Targeting Visitors Using Attributes List in VWO.

In this article, we’ll get down to the real basics about the Attributes List, i.e., how things work in the background (the technical aspects) while working with the Attributes List feature. Let’s understand what happens when you upload the Attributes List and use it as a targeting condition through an example. 

Consider the following:

Scenario

1. Attributes List of Premium Users is targeting visitors using a JavaScript Variable(say premiumUserIdentifier) in a campaign C1
2. In the Segment Settings of the campaign following options are chosen
   • "Poll Until" option is set to "Condition is true"
   • "Check targeting conditions for a visitor" option is set to "Always"
3. premiumUserIdentifier variable is set on the page after a few seconds.
4. The campaign is modifying the Headline of the pages P1, P2.

Terminology

1. P{n} - Page Number n
2. V{n} - Visitor number n
3. A variable is considered to be available if its value is neither false nor undefined nor null

Flow

1. 1. 1. V1 visits P1 on which the premiumUserIdentifier variable is available after a few seconds with a value that exists in the list.
      2. As soon as the VWO library is fetched, it would not be able to determine if the value of the premiumUserIdentifier exists in the list or not. So, the targeting condition would remain false.
         
         NOTE: It doesn’t matter if the Targeting is “premiumUserIdentifier IN LIST” or “premiumUserIdentifier NOT IN LIST”. In both cases, the targeting condition would remain false as the lookup result is not yet available in the browser’s localStorage.
      3. As the "Poll Until" option is set to "Condition is true", the VWO library would wait for the value of premiumUserIdentifier to be available.
      4. Once the variable is available, an asynchronous request for checking the value in the list (i.e., a POST request to https://dev.visualwebsiteoptimizer.com/sync) would be sent along with the required info, and the response would contain the result for the lookup in the list. In this case, there will be a positive result of the lookup as the JavaScript Variable premiumUserIdentifier value exists in the list.
      5. The result for the asynchronous request is cached in the browser (in localStorage) for faster evaluation the next time the visitor returns to the page.
      6. The time it takes for the value to be checked in the list (i.e., Step 4) to complete would be the additional time for which the Headline (on which change has been applied) would remain hidden.
         
         NOTE: This is why the Attributes List approach is not the best way to target visitors if the number of items in the list is less. Let’s say that the items in the list are just puser1 and puser2, then a better way to solve the same problem is by adding the condition as “JavaScript Variable premiumUserIdentifier is equal to puser1”, OR “JavaScript Variable premiumUserIdentifier is equal to puser2”.
      7. The Targeting condition would be met, and V1 would see one of the versions of campaign C1.
         
         NOTE: Had the “Poll Until” option been set to “Polling Disabled”, the targeting condition would not have met as the VWO library would not have wait for the premiumUserIdentifier variable to be available.
      8. V1 revisits P1, and here as the "Check targeting conditions for a visitor" option is set to "Always", V1 would be rechecked for the targeting condition (ignoring that V1 has once seen a specific version of C1).
      9. This time as the lookup result is first checked in the browser cache (in localStorage), the result of the targeting condition can be evaluated instantly, avoiding the need for a call to check values. It makes the repeat experience of the visitor smooth even if the "Check targeting conditions for a visitor" option is set to "Always".
         

Have any questions about this feature? Refer to Attributes List FAQs.