<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.6/angular.min.js"></script>

<div ng-app="TestApp">

    <div ng-controller="TestCtrl">

        <span>{ { prop}}</span>

        <button id="btn" ng-click="on_btn_click()">button</button>

    </div>

</div>

<script>

    var app = angular.module("TestApp", []);

    var ctrl = app.controller("TestCtrl", function($scope) {

        $scope.prop = 0;

    

        $scope.on_btn_click = function() {

            $scope.prop++;

        }

    })

</script>