javascript - Angular form validation seems to add class of ng-xx-required whether input is required or not? -

when input required, ng-invalid-required added class , required="required" being set attribute.

when input not required, ng-valid-required added class , no required attribute being set attribute.

(a way add required input, through setting variable on scope , using ng-required per plunkr.)

here plunkr example 1 required input , 1 non required input

what struggling trying find specific documentation on ng-valid-required. feel confused why there's class ng-xx-required, when input not required.

thanks in advance time. rock on!

it working solution:

<input type="text" name="username" ng-model="user.name" ng-required="required"> 

the problem pearhaps in variable definition see plunker here: http://plnkr.co/edit/dbcwdeukjq8zp1b3daov?p=preview