Counting The Number Of Watchers In AngularJS - Updated For Isolate Scopes

get-watch-count.js

// I return the count of watchers on the current page.
function getWatchCount() {

	// Keep track of the total number of watch bindings on the page.
	var total = 0;

	// There are cases in which two different ng-scope markers will actually be referencing
	// the same scope, such as with transclusion into an existing scope (ie, cloning a node
	// and then linking it with an existing scope, not a new one). As such, we need to make
	// sure that we don't double-count scopes.
	var scopeIds = {};

	// AngularJS denotes new scopes in the HTML markup by appending the classes "ng-scope"
	// and "ng-isolate-scope" to appropriate elements. As such, rather than attempting to
	// navigate the hierarchical Scope tree, we can simply query the DOM for the individual
	// scopes. Then, we can pluck the watcher-count from each scope.
	// --
	// NOTE: Ordinarily, it would be a HUGE SIN for an AngularJS service to access the DOM
	// (Document Object Model). But, in this case, we're not really building a true AngularJS
	// service, so we can break the rules a bit.
	angular.forEach(
		document.querySelectorAll( ".ng-scope , .ng-isolate-scope" ),
		countWatchersInNode
	);

	return( total );


	// ---
	// PRIVATE METHODS.
	// ---


	// I count the $watchers in to the scopes (regular and isolate) associated with the given
	// element node, and add the count to the running total.
	function countWatchersInNode( node ) {

		// Get the current, wrapped element.
		var element = angular.element( node );

		// It seems that in earlier versions of AngularJS, the separation between the regular
		// scope and the isolate scope where not as strong. The element was flagged as having
		// an isolate scope (using the ng-isolate-scope class); but, there was no .isolateScope()
		// method before AngularJS 1.2. As such, in earlier versions of AngularJS, we have to
		// fall back to using the .scope() method for both regular and isolate scopes.
		if ( element.hasClass( "ng-isolate-scope" ) && element.isolateScope ) {

			countWatchersInScope( element.isolateScope() );

		}

		// This class denotes a non-isolate scope in later versions of AngularJS; but,
		// possibly an isolate-scope in earlier versions of AngularJS (1.0.8).
		if ( element.hasClass( "ng-scope" ) ) {

			countWatchersInScope( element.scope() );

		}

	}


	// I count the $$watchers in the given scope and add the count to the running total.
	function countWatchersInScope( scope ) {

		// Make sure we're not double-counting this scope.
		if ( scopeIds.hasOwnProperty( scope.$id ) ) {

			return;

		}

		scopeIds[ scope.$id ] = true;

		// The $$watchers value starts out as NULL until the first watcher is bound. As such,
		// the $$watchers collection may not exist yet on this scope.
		if ( scope.$$watchers ) {

			total += scope.$$watchers.length;

		}

	}

}