angular $emit发送 后退时$on多次接收

$rootScope.$on('saveDraft', function() {
$scope.saveDraft();
});
$rootScope.$on('previewPosition', function() {
$scope.previewPosition();
});
$rootScope.$on('publishJob', function() {
$scope.publishJob();
});

$scope.previewPosition = function() {
$scope.$emit('previewPosition');
};
$scope.saveDraft = function() {
$scope.$emit('saveDraft');
};
$scope.publishJob = function() {
$scope.$emit('publishJob');
};

$scope.$on('saveDraft', function() {
$scope.saveDraft();
});
$scope.$on('previewPosition', function() {
$scope.previewPosition();
});
$scope.$on('publishJob', function() {
$scope.publishJob();
});

$scope.previewPosition = function() {
$rootScope.$broadcast('previewPosition');
};
$scope.saveDraft = function() {
$rootScope.$broadcast('saveDraft');
};
$scope.publishJob = function() {
$rootScope.$broadcast('publishJob');
};