Use a Shared Storage worklet to run A/B testing.
The Shared Storage API is a Privacy Sandbox proposal for general purpose, cross-site storage, which supports many possible use cases. One such example is A/B testing, which is available to test in Chrome 104.0.5086.0 and later.
You can assign a user to an experiment group, then store that group in Shared Storage to be accessed in a cross-site environment.
Try A/B testing
To experiment with A/B testing with Shared Storage, confirm you're using Chrome 104.0.5086.0 or later. Enable all the Ad privacy APIs under chrome://settings/adPrivacy
.
You can also enable Shared Storage with the --enable-features=PrivacySandboxAdsAPIsOverride,OverridePrivacySandboxSettingsLocalTesting,SharedStorageAPI,FencedFrames
flag in the command line.
Experiment with code samples
To see if an experiment has the desired effect, you can run A/B testing across multiple sites. As an advertiser or a content producer, you can choose to render different content or ads based on what group the user is assigned to. The group assignment is saved in shared storage, but cannot be exfiltrated.
In this example:
-
ab-testing.jsshould be embedded in a frame, which maps a control and two experiment contents. The script calls the shared storage worklet for the experiment. -
ab-testing-worklet.jsis the shared storage worklet that returns which group the user is assigned to, determining which ad is shown.
// Randomly assigns a user to a group 0 or 1
function
getExperimentGroup
()
{
return
Math
.
round
(
Math
.
random
());
}
async
function
injectContent
()
{
// Register the Shared Storage worklet
await
window
.
sharedStorage
.
worklet
.
addModule
(
'ab-testing-worklet.js'
);
// Assign user to a random group (0 or 1) and store it in Shared Storage
window
.
sharedStorage
.
set
(
'ab-testing-group'
,
getExperimentGroup
(),
{
ignoreIfPresent
:
true
,
});
// Run the URL selection operation
const
fencedFrameConfig
=
await
window
.
sharedStorage
.
selectURL
(
'ab-testing'
,
[
{
url
:
`https://your-server.example/content/default-content.html`
},
{
url
:
`https://your-server.example/content/experiment-content-a.html`
}
],
{
resolveToConfig
:
true
}
);
// Render the chosen URL into a fenced frame
document
.
getElementById
(
'content-slot'
).
config
=
fencedFrameConfig
;
}
injectContent
();
class
SelectURLOperation
{
async
run
(
urls
,
data
)
{
// Read the user's experiment group from Shared Storage
const
experimentGroup
=
await
sharedStorage
.
get
(
'ab-testing-group'
);
// Return the corresponding URL (first or second item in the array)
return
urls
.
indexOf
(
experimentGroup
);
}
}
register
(
'ab-testing'
,
SelectURLOperation
);
Use cases
All available use cases for Select URL API can be found in this section. We'll continue to add examples as we receive feedback and discover new test cases.
- Rotate ad creatives : Store data, such as creative ID and user interaction, to determine which creative users' see across different sites.
- Select ad creatives by frequency : Use view count data to determine which creative users' see across different sites.
- Run A/B testing : You can assign a user to an experiment group, then store that group in Shared Storage to be accessed cross-site.
- Customize experience for known customers : Share custom content and calls-to-action based on a user's registration status or other user states.
Engage and share feedback
Note that the Select URL API proposal is under active discussion and development and subject to change.
We're eager to hear your thoughts on the Select URL API.
- Proposal: Review the detailed proposal .
- Discussion: Join the ongoing discussion to ask questions and share your insights.
Stay Informed
- Mailing List: Subscribe to our mailing list for the latest updates and announcements related to the Select URL and Shared Storage APIs.
Need Help?
- Developer Support: Connect with other developers and get answers to your questions in the Privacy Sandbox Developer Support repository .
