JSFiddle - React, Tailwind, and code Playground
HTML
<div ng-app>
<form name="myForm" ng-controller="ctrl">
<input type="text" ng-model="name" ng-required="true" />
<span>{{name}}</span>
<input type="submit" value="Submit" ng-disabled="myForm.name.$pristine" />
</form>
</div>
JavaScript
function ctrl($scope){
$scope.name = "hello";
}