JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.3.0-beta.19/angular.min.js"></script>
<section ng-app="application">
    <section ng-controller="main">
        <section ng-if="xxx">
            <div>
                <input ng-model="test" />
            </div>
        </section>
    </section>
</section>

JavaScript

application = angular.module('application', []);
application.controller('main', ['$scope', function ($scope) {
    
    $scope.xxx = true;
    
    $scope.$watch('test', function () {
        alert('$scope.test was changed!')
    });
}]);