Extend cookie lifetime

Disable or enable the automatic lifetime extension of the visitor ID cookie.



Parameter and Type

Child Attribute



An object with the type field set to extendCookieLifetime. The other fields are the function arguments. Required.


Child attribute of type ExtendCookieLifetimeObject

The argument indicating that you're using the extendCookieLifetime function. Required.


Child attribute of type ExtendCookieLifetimeObject

Set to false to prevent Optimizely from extending the lifetime of existing cookies when the snippet activates.

Example Call

  "type": "extendCookieLifetime",
  "isEnabled": false


By default, whenever the snippet activates, it resaves any existing Optimizely visitor ID cookie onto the currently configured cookieDomain and with the currently configured cookieExpiration.

For example, if you use the Cookie Expiration API to specify a lifetime of 365 days, you can use Extend Cookie Lifetime to disable the automatic lifetime extension, ensuring the cookie’s expiration does not get refreshed on each snippet activation. As a result, the cookie would expire 365 days after it was created.

Call this API with isEnabled: false to prevent Optimizely from automatically extending the expiration period of the visitor ID cookie.

  • A visitor ID cookie whose value does not change during snippet activation (e.g., most returning visitors') will retain the original domain and expiration date that were specified when the cookie was set (during a prior snippet activation).
  • A visitor ID cookie that is new (e.g., a new visitor's) or whose value is modified (due to having been synchronized from another origin via waitForOriginSync, for example), will be set as normal, using the currently-configured cookieDomain and cookieExpiration.

You must call this prior to each snippet initialization to suppress the cookie-extending behavior.