Tag Manager Custom JavaScript Trigger and Custom Variable to track a third-party iFrame interaction

GTM Custom JavaScript Trigger

// Add focus on current window
window.focus();

// When click on iframe the focus change and we are listen this
var listener = window.addEventListener('blur', function() {
	
	//console.log('active == iFrame: ', document.activeElement == document.querySelector('iframe[title="Help Scout Beacon"]'));
	
	// if the current focus is on your iFrame (you can use any css or js selector here)
	if (document.activeElement == document.querySelector('iframe')) {
		
		//console.log('clicked');
		
		// Add to dataLayer your information
		window.dataLayer = window.dataLayer || [];        
		window.dataLayer.push({
		  'chatBtn': true,
		  'event': 'chatBtn'
		});
	 }
	
	// Remove listener
 	window.removeEventListener('blur', listener);
});