> For the complete documentation index, see [llms.txt](https://help.felt.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://help.felt.com/developer-platform/javascript-sdk.md). # JavaScript SDK {% embed url="" %} Felt's user interface allows a large amount of customization, offering the ability to generate complex cartographic designs, adding components to create a dashboard, and much more. However, sometimes application developers need further control over the experience of viewing and/or interacting with a map. For example, they may want to run custom logic after a user clicks on a feature in a layer, or animate data on the map based on other types of user input elsewhere on the webpage. For these situations and many more, Felt's [**JavaScript SDK**](https://developers.felt.com/js-sdk/getting-started) allows developers to load a Felt map into their application while providing opportunities to hook into the interaction loop and more broadly customize the experience of the map viewer. The SDK also powers [Extensions](/developer-platform/extensions.md) — custom tools that run inside Felt itself, with AI drafting the SDK code for you. Visit our [Developer docs](https://developers.felt.com/) for comprehensive documentation, code examples, and guides to get started. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://help.felt.com/developer-platform/javascript-sdk.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.