---
title: JavaScript (Browser) SDK prior to v6
slug: feature-experimentation/docs/javascript-sdk-prior-to-v6
docTags: 
createdAt: 2026-08-05T20:39:52.000Z
---

## Version

This documentation is for JavaScript SDK versions 5.3.5 and earlier.

For the latest JavaScript documentation, see [JavaScript SDK](docId:8PWUc59E_yQaRlOmUc5JA).

See the [SDK compatibility matrix](docId:2shbZfPCkPAZ0mlZpL1TU) documentation for a list of current SDK releases and the features they support.

## Reference

For reference documentation, see the left-hand menu, or start by [installing the JavaScript (Browser) SDK](docId\:k5-eIbD1aBpIDrLvDA8KH).

## Source files

You can find the [JavaScript SDK repository](https://github.com/optimizely/javascript-sdk) and [Releases](https://github.com/optimizely/javascript-sdk/releases) on GitHub.