Required
Ensures the value of field under validation is not empty.
#Directive Code Snippet
<!DOCTYPE html>
<html lang="en">
...
<form (ngSubmit)="onSubmit(form)" #form="ngForm">
<input [required] type="text" name="<name>" [(ngModel)]="<name>" #<name>="ngModel">
</form>
...
</html>
#Chain Rule Code Snippet
<!DOCTYPE html>
<html lang="en">
...
<form (ngSubmit)="onSubmit(form)" #form="ngForm">
<input [Rule]="required" type="text" name="<name>" [(ngModel)]="<name>" #<name>="ngModel">
</form>
...
</html>