Google Analytics send event callback function

Finally got it. It's pretty complicated and not described in docs. In my case I use Google Tag Manager, so there some workarounds I had to make to get successfully fire an event and get callback.

First, we have to get ClientId, which is required with any event sent to Google servers. Actually it's kept in cookies, but Google does not recommend to take it directly from there.

Here is how Google recommends to get it, but this will not work if you are using Google Tag Manager.

 ga(function(tracker) {
       var clientId = tracker.get('clientId');
 });

Instead, you have to get ClientId from getAll method.

 var clientId = ga.getAll()[0].get('clientId');

After, you have to create new tracker

    ga('create', 'UA-XXX-YYY', {
        'clientId': clientId
    });

And after that we can send an event:

 ga('send', 'event', {
   'eventCategory': 'YOUR Category Name', //required
   'eventAction': 'YOUR Action name', //required
   'eventLabel': 'YOUR Label',
   'eventValue': 1,
   'hitCallback': function() {
       console.log('Sent!!');
      //callback function
    },
   'hitCallbackFail' : function () {
      console.log("Unable to send Google Analytics data");
      //callback function
   }
});

From Google Analytic doc https://developers.google.com/analytics/devguides/collection/analyticsjs/field-reference#hitCallbackNews

// Alerts the user when a hit is sent.
ga('send', 'pageview', {
  'hitCallback': function() {
    alert('hit sent');
  }
});

You can edit the hitCallback function for yours.

OR

// Use a timeout to ensure the execution of critical application code.
ga('send', 'pageview', {'hitCallback': criticalCode});
setTimeout(criticalCode, 2000);

// Only run the critical code once.
var alreadyCalled = false;
function criticalCode() {
  if (alreadyCalled) return;
  alreadyCalled = true;

  // Run critical code here...
}

Here you can define your function (criticalCode) in the above example that can ensure the data sent to Google Analytic and then work with your code.

For much understanding api of analytic, fyr: https://developers.google.com/analytics/devguides/collection/analyticsjs/command-queue-reference