Automatic trace logging of Angular.js events and ui-router state transitions

ui-router-logging.js

angular.module('your-module').config(['$provide', function ($provide) {
    $provide.decorator('$rootScope', ['$delegate', function ($delegate) {
        wrapMethod($delegate, '$broadcast', function (method, args) {
            if (isNonSystemEvent(args[0]))
                logCall('$broadcast', args);

            return method.apply(this, args);
        });

        wrapMethod($delegate, '$emit', function (method, args) {
            if (isNonSystemEvent(args[0]))
                logCall('$emit', args);

            return method.apply(this, args);
        });

        return $delegate;

        function isNonSystemEvent(eventName) {
            return eventName && eventName[0] && eventName[0] !== '$';
        }
    }]);
        
    $provide.decorator('$state', ['$delegate', function ($delegate) {
        wrapMethod($delegate, 'go', function (method, args) {
            logCall('$state.go', args);

            return method.apply(this, args);
        });

        return $delegate;
    }]);

    function wrapMethod(obj, methodName, wrapper) {
        var original = obj[methodName];

        obj[methodName] = function () {
            var args = Array.prototype.slice.call(arguments, 0);
            return wrapper.call(this, original, args);
        };
    }

    function logCall(funcName, args) {
        var prettyArgs = args.map(function (a) { return repr(a) })
            .join(', ');
        console.log(funcName + '(' + prettyArgs + ')');
    }

    function repr(obj) {
        return JSON.stringify(obj, function (k, v) {
            if (k !== '' && v instanceof Object)
                return '[Obj]';
            else
                return v;
        });
    }
}]);