JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.2.1/angular-sanitize.js"></script>
<div ng-app="myApp" ng-controller="dummy">
    <ul>
        <li ng-init="formData.mdpSunday='5'">
            <input ng-model="formData.mdpSunday" name="mdpSunday" type="radio" value="5">
        </li>
    </ul>
</div>

JavaScript

angular.module('myApp', ['ngSanitize'])
    .controller('dummy', ['$scope', function ($scope) {

    $scope.formData = {};

    $scope.$watch('formData.mdpSunday', function (newVal, oldVal) {
        console.log(oldVal);
    });
}]);