Proper way to restrict text input values (e.g. only numbers)

In component.ts add this function

_keyUp(event: any) {
    const pattern = /[0-9\+\-\ ]/;
    let inputChar = String.fromCharCode(event.key);

    if (!pattern.test(inputChar)) {
      // invalid character, prevent input
      event.preventDefault();
    }
}

In your template use the following

<input(keyup)="_keyUp($event)">

This will catch the input before angular2 catches the event.