CODEWITHSUNDEEP
angularjshttp
Emjey23
Emjey23

Reputation: 367

AngularJS callback error and is not a function

I have an error in line callback(response.data) telling that callback is not a function. Well, I am new to this and I am trying to figure out how to fix this issue but I am having a tough time. Any idea is appreciated. Thanks 

 app.service('NotificationPollService', function ($q, $http, $timeout) {

      var notification = {};
      notification.poller = function (callback, error) {
          return $http.get('api/sample.php').then(function (response) {
              if (typeof response.data === 'object') {
                  callback(response.data);                 
              } else {
                  error(response.data);
              }
              $timeout(notification.poller, 2000);
          });
      }

      notification.poller();

      return notification;
});

Upvotes: 0

Views: 308

Answers (1)

DWilches
DWilches

Reputation: 23035

You declared poller as a function that receives two functions as its parameters, but you are invoking it with no parameters in two different places: 

    notification.poller();

and

    $timeout(notification.poller, 2000);

Remember you can log the value of the variables to the console as console.log(callback, error), in which case you will see it prints undefined, undefined.

What was the intention of invoking notification.poller() in that line? Looks like that function should be called by the user of your service instead, like this:

    notification.poller(data => console.log(`Received some data! ${data}`),
                        error => console.error(`Some error occurred: ${error}`));

Lastly, what is the intention of poller? By the name I imagined it was going to invoke that endpoint some fixed X number of times (polling) and after X failures it would give up, but it's always invoking poller again, even after a success.

Upvotes: 2

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