ng 通过factory方法来创建一个心跳服务

<!DOCTYPE html>
<html ng-app="myApp">
<head lang="en">
  <meta charset="UTF-8">
  <script src="js/angular.js"></script>
  <title></title>
</head>
<body>
<div ng-controller="myCtrl">
  <button ng-click="start()">开始</button>
  <button ng-click="stop()">结束</button>
</div>
<script>
  var app = angular.module('myApp', ['ng']);

  //通过factory方法来创建一个心跳服务
  app.factory('$heartBeat', function ($interval) {
    return {
      startBeat: function () {
         promise = $interval(
          function () {
            console.log('in heart Beat..');
          },
          500)
      },
      stopBeat: function () {
        $interval.cancel(promise);
      }
    }
    1
  });

  app.controller('myCtrl', function ($scope,$heartBeat) {

    $scope.start = function () {
      $heartBeat.startBeat();
    }
    
    $scope.stop = function () {
      $heartBeat.stopBeat();
    }
    
  })
</script>
</body>
</html>