Catch javascript errors inside google analytics

Question

I want the window.onerror handler to be called when an error occures inside the "ga(function(tracker)" function. Apparently the ga function has it's own error handler which prevents the window.onerror handler to be invoked.

(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','//www.google-analytics.com/analytics.js','ga');

window.onerror = function() {console.log('Hello world') };
    
ga('create', '********', '********');
ga(function(tracker) {
console.log('Start');
/* 
Variable y is undefined 
window.onerror should be invoked
*/
var x = y;
console.log('End');
});
ga('send', 'pageview');

Just to be clear. My question is NOT how to track errors with google analytics but how to catch errors inside google analytics scripting.

Does this answer your question? Report for exceptions from Google Analytics analytics.js exception tracking — Michele Pisani
– Michele Pisani, Commented Sep 8, 2020 at 10:28
@MichelePisani Thanks for replying. No my question is not how to track javascript errors with google analytics but how to track errors inside the javascript of google analytics. — Nebu
– Nebu, Commented Sep 8, 2020 at 10:51
What kind of error would you like to track within the analytics code? — Michele Pisani
– Michele Pisani, Commented Sep 8, 2020 at 20:25
@MichelePisani All errors. If an error occurs inside this part of the script it is possible a pageview/event/etc is not send to google analytics. We track all javascript errors on our website via the window.onerror event. However for some reason the window.onerror is not invoked for errors inside the ga scripts. This means it can take a while before we notice a problem. — Nebu
– Nebu, Commented Sep 9, 2020 at 10:45

Дмитро Булах · Accepted Answer · 2020-09-11 10:19:47Z

1

using custom try..catch and dispatchEvent would help:

    
ga('create', '********', '********');

// declaring readyCallback function
var initFunction = function(tracker) {
console.log('Start');
/* 
Variable y is undefined 
window.onerror should be invoked
*/
var x = y;
console.log('End');
}

// Wrapping your readyCallback with custom try...catch:
var initFunctionWrapped = function (tracker) {
  try {
    initFunction(tracker)
  } catch (e) {
    var event = new Event('error', e);
    window.dispatchEvent(event)
}

ga(initFunctionWrapped);
ga('send', 'pageview');

answered Sep 11, 2020 at 10:19

Дмитро Булах

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2 Comments

Nebu Over a year ago

If the initFunction returns an error why is it caught using the initFunctionWrapped function but not caught if called directly by the window.onerror handler?

Дмитро Булах Over a year ago

If you don't use dispatchEvent any error in readyCallback will be caught by ga inner try...catch and won't propagate to window

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