copy attachment from Mail then paste with Javascript

HI.

1. I copy one Attachment from Apple Mail
2. then I paste it using an handler written with Javascript

The past event contains a DataTransfer object of type text/html containing the following <attachment tag :

<attachment webkitattachmentid="c720819f-a3a3-4d71-af65-b5419bd23a4f"

id="<e3b45dd0-e6da-4c7c-bd1a-56bed389f8ca>"

title="photo couché de soleil sur la voilerie.jpeg"

type="image/jpeg"

role="button"

aria-label="photo couché de soleil sur la voilerie.jpeg"

class="Apple-web-attachment"

src="<e3b45dd0-e6da-4c7c-bd1a-56bed389f8ca>"

subtitle="264 ko"

style="caret-color: rgb(0, 0, 0); color: rgb(0, 0, 0); font-family: Arial, Helvetica, sans-serif; font-size: 18.666666px; font-style: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: auto; text-align: center; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration: none;">

</attachment>

How to get the file corresponding to this attachment with Javascript ?

Thanks in advance for any help.