Custom widget, javascript, get current user email

In a custom widget, I try to get the email of the current user in the javascript. How would I do that?

Thanks in advance

I now answer to myself: I now created a system user table. I put row based access control to that table. I can then only see my own row. I can then query that table via plugin api and get only my own row back. I now have all the system user details available in the custom widget.