So, I found that our client JavaScript was recording quite a lot of successful dependency messages for loading 3rd party scripts:

Therefore, I wrote a telemetry filter to block sending them. I could just use sampling – but I’d prefer to have none.

onInit: function (sdk) {
	/*	Once the application insights instance has loaded and initialized this method will be called 
	    This filter will block successful remote dependency requests being logged. */
	sdk.addTelemetryInitializer(function(envelope) {
		if (envelope.baseType === 'RemoteDependencyData')
		{
			if (envelope.baseData.success)
			{
				return false;
			}
		}
	});
},

From my testing, if the user blocks loading of a remote dependency I don’t see any kind of message being returned – even a failure, which is good.

So, we are using App Insights, and when we moved the client side script for recording JavaScript errors to our integration test instance we started to get a lot of errors of the form:

Script error: The browser’s same-origin policy prevents us from getting the details of this exception. Consider using the ‘crossorigin’ attribute.

There were a lot of these errors:

… and investigating them showed that the problems came from 3rd party JavaScript. All of these are inserted by Google Tag Manager, and aren’t in the site, or local development.

Well, I’m not going to be able to fix JavaScript written by 2 third-parties, and that isn’t even loaded directly by my page – so instead I’m going to ignore that error…

Continue reading “Filtering App Insights Client Exceptions from 3rd party JavaScript” →