In this example last name textbox will be created if
ng-if expression evaluates true i.e first name textbox neither be null nor empty. In our example, we have two textboxes one with
ng-model="firstName" and second with
ng-model="lastName", but there is span outside lastname textbox with
ng-if="firstName!=null && firstName!=''" so if there will be any value in first textbox only then the second textbox will be visible.