title: Checking whether an Angular4 form is valid or not from within the component
body: <p>The following <a href="https://stackoverflow.com/a/37240284/3534027">answer</a> deals with Angular2, but since there have been a number of changes to Angular in Angular4 with forms, this solution does not work.  Anyone have any idea on how to do this (without having to deal with FormGroups, etc).  Basically, how can I get that answer work with Angular4?</p>