Untitled

<!DOCTYPE html>
<html>
<script
 src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.4/angular.min.js">
</script>
<body>
<div ng-app="myApp" ng-controller="myCtrl">

First Name: <input type="text" ng-model="firstName"><br>
is Branch Manager? <input type="checkbox" ng-model="checkbox"><br>
<button name="subject" type="submit" value="Save">Save</button>
<br>


</div>

<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.function = function(){
        if($scope.checkbox)
        {
            if($("#firstName").isEmpty())
            {
                alert("first name is empty");
            }
        }
});
</script>

</body>
</html>