subscribeCartItem()

Subscribes a cart item to a subscription plan.

Signature

await window.FairShareSDK.subscribeCartItem(itemId, subscriptionPlanId);

Parameter	Type	Description
`itemId`	number	Cart item ID
`subscriptionPlanId`	number	Subscription plan ID

// Subscribe item to a plan
await window.FairShareSDK.subscribeCartItem(123, 456);