Use JS SDK to save payment methods (for purchase-later transactions)

You can use the PayPal JavaScript SDK to save a payer’s payment method and use it for future transactions that do not involve checkout or require the payer’s presence. For example, you can use the saved payment method to bill the payer after a free trial period.    

If your Checkout integration is a client and server-side integration, using the JS SDK you can,  

• Save credit and debit cards. 
• Save PayPal wallets.   

If your Checkout integration is a client-side integration, using the JS SDK, you can save the payer’s PayPal wallets.