---
title: JavaScript API use cases
slug: web-experimentation/docs/personalization-use-cases
docTags: 
createdAt: 2026-07-23T11:40:24.851Z
---

When running Optimizely Personalization, your web page can evaluate a behavioral query on-demand using the query API.

- This type of behavioral query can evaluate to a complex value like a list or an event object, in addition to a simple value like a number, Boolean, or string.
- You can analyze even more complex behavior by making multiple calls to the JavaScript API.
- You can also use the JavaScript API to debug behavioral queries that you are planning to use in your Custom Behavioral Attributes.