---
title: Cookie Domain
slug: performance-edge/api/cookie-domain
docTags: 
createdAt: 2026-06-23T07:33:02.005Z
---

Instruct Optimizely Performance Edge to set its cookies on a specific subdomain instead of the default domain.

## Description

Instruct Optimizely Performance Edge to set its cookies on a specific subdomain instead of the default domain. You must call `setCookieDomain` prior to loading the Optimizely Performance Edge snippet. By default, Optimizely Performance Edge sets its cookies on the domain, in order to work across subdomains.

```javascript
window.optimizelyEdge.push(cookieDomain);
```

```javascript
window.optimizelyEdge.push({
  "type": "cookieDomain",
  "cookieDomain": "www.example.com"
});
```

## Parameters

This table provides general information about required and optional parameters.

| Parameters                               | Type   | Description                                                               |
| ---------------------------------------- | ------ | ------------------------------------------------------------------------- |
| **cookieDomain** *required*              | object | An object with the type field set to cookieDomain.                        |
| **cookieDomain.type** *required*         | string | The argument indicating that you are using the cookieExpiration function. |
| **cookieDomain.cookieDomain** *optional* | string | The cookie domain.                                                        |

:::BlockQuote
📘 Note

This API is ignored when setting the [`optimizelyRedirectData cookie`](https://help.optimizely.com/Set_Up_Optimizely/Cookies_and_localStorage_in_the_Optimizely_snippet#First-party_cookies_in_Optimizely_X), used for forwarding redirect experiment info to the new page.
:::