How to write custom form controls in Angular

we all love two-way data bindings right?. we love when we add “NgModel” directive to some input and values are synced one way another. It’s a really cool feature. but things got’s interesting when we want to add this functionality to our custom component, for example, a component like this

we have two buttons, and when we click “plus” it increases by one when we click “minus” it…