JavaScript is of course client based so doesn't have the capabilities as say C# on the server. To send email, without calling some server-side code, you are basically limited to mailto
You can redirect to a
mailto:someone@example.com?cc=someone_else@example.com&subject=This%20is%20the%20subject&body=This%20is%20the%20body
address which tells the browser to fire up the mail client which then makes the mail ready to send - the user just has to hit "submit".
Code:
document.location="mailto:someone@example.com?cc=someone_else@example.com&"+
"subject=This%20is%20the%20subject&body=This%20is%20the%20body";