The JAMA (AMA 10th) endnote output style (updated 2018-07-05) Download here: https://endnote.com/downloads/styles/?wpv_post_search=jama&wpv_aux_current_post_id=12829&wpv_view_count=12764-TCPID12829
has this Web Page Bibliography Template
Author. Title. Publisher. Series Title Web site. URL.| Published Year.| Updated Last Update Date.| Accessed| Access Date, Access Year|.
So if you have entered data into those fields in the record, have assigned the appropriate Ref type for the record and are using the JAMA output style in the Endnote Ribbon (See attached) - it should be there in the bibliography. See my exammple of what the record looks like, what the preview of the bibliography listing should look like.
