How to create helper class that can accessed with controller on AngularJS

how can I create a helper/utility class that can be accessible from the multiple controllers?

For example, I have two controllers: UpdateItemCtrl and CreateItemCtrl. These have common functions inside which increases redundancy and lowers managability.

I'd like to create a ItemSaveHelper class which I would put the common methods inside and call them from the active controller.

You want to create a service.

A service is just a singleton that can be injected into different things to provide modular/shared functionality. Here's a simple example: http://jsfiddle.net/andytjoslin/pHV4k/

function Ctrl1($scope, itemManager) {
    $scope.addItem = function(text) {
        itemManager.items.push(text);
    };
}

function Ctrl2($scope, itemManager) {
    $scope.items = itemManager.items;
}

app.factory('itemManager', function() {
    return {
        items: []
    };
});