Returns the user-agent
header as sent from the device used to make the router request.
export function myRouter_Router(request) {
let userAgent = request.userAgent;
// "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_12_4) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/57.0.2987.133 Safari/537.36"
}