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Can I make a function available in every controller in angular?

Posted by: admin November 2, 2017 Leave a comment

Questions:

If I have a utility function foo that I want to be able to call from anywhere inside of my ng-app declaration. Is there someway I can make it globally accessible in my module setup or do I need to add it to the scope in every controller?

Answers:

You basically have two options, either define it as a service, or place it on your root scope. I would suggest that you make a service out of it to avoid polluting the root scope. You create a service and make it available in your controller like this:

<!doctype html>
<html ng-app="myApp">
<head>
    <script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
    <script src="http://code.angularjs.org/1.1.2/angular.min.js"></script>
    <script type="text/javascript">
    var myApp = angular.module('myApp', []);

    myApp.factory('myService', function() {
        return {
            foo: function() {
                alert("I'm foo!");
            }
        };
    });

    myApp.controller('MainCtrl', ['$scope', 'myService', function($scope, myService) {
        $scope.callFoo = function() {
            myService.foo();
        }
    }]);
    </script>
</head>
<body ng-controller="MainCtrl">
    <button ng-click="callFoo()">Call foo</button>
</body>
</html>

If that’s not an option for you, you can add it to the root scope like this:

<!doctype html>
<html ng-app="myApp">
<head>
    <script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
    <script src="http://code.angularjs.org/1.1.2/angular.min.js"></script>
    <script type="text/javascript">
    var myApp = angular.module('myApp', []);

    myApp.run(function($rootScope) {
        $rootScope.globalFoo = function() {
            alert("I'm global foo!");
        };
    });

    myApp.controller('MainCtrl', ['$scope', function($scope){

    }]);
    </script>
</head>
<body ng-controller="MainCtrl">
    <button ng-click="globalFoo()">Call global foo</button>
</body>
</html>

That way, all of your templates can call globalFoo() without having to pass it to the template from the controller.

Questions:
Answers:

You can also combine them I guess:

<!doctype html>
<html ng-app="myApp">
<head>
    <script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>
    <script src="http://code.angularjs.org/1.1.2/angular.min.js"></script>
    <script type="text/javascript">
        var myApp = angular.module('myApp', []);

        myApp.factory('myService', function() {
            return {
                foo: function() {
                    alert("I'm foo!");
                }
            };
        });

        myApp.run(function($rootScope, myService) {
            $rootScope.appData = myService;
        });

        myApp.controller('MainCtrl', ['$scope', function($scope){

        }]);

    </script>
</head>
<body ng-controller="MainCtrl">
    <button ng-click="appData.foo()">Call foo</button>
</body>
</html>

Questions:
Answers:

Though the first approach is advocated as ‘the angular like’ approach, I feel this adds overheads.

Consider if I want to use this myservice.foo function in 10 different controllers. I will have to specify this ‘myService’ dependency and then $scope.callFoo scope property in all ten of them. This is simply a repetition and somehow violates the DRY principle.

Whereas, if I use the $rootScope approach, I specify this global function gobalFoo only once and it will be available in all my future controllers, no matter how many.

Questions:
Answers:

AngularJs has “Services” and “Factories” just for problems like yours.These are used to have something global between Controllers, Directives, Other Services or any other angularjs components..You can defined functions, store data, make calculate functions or whatever you want inside Services and use them in AngularJs Components as Global.like

angular.module('MyModule', [...])
  .service('MyService', ['$http', function($http){
    return {
       users: [...],
       getUserFriends: function(userId){
          return $http({
            method: 'GET',
            url: '/api/user/friends/' + userId
          });
       }
       ....
    }
  }])

if you need more

Find More About Why We Need AngularJs Services and Factories

Questions:
Answers:

I’m a bit newer to Angular but what I found useful to do (and pretty simple) is I made a global script that I load onto my page before the local script with global variables that I need to access on all pages anyway. In that script, I created an object called “globalFunctions” and added the functions that I need to access globally as properties. e.g. globalFunctions.foo = myFunc();. Then, in each local script, I wrote $scope.globalFunctions = globalFunctions; and I instantly have access to any function I added to the globalFunctions object in the global script.

This is a bit of a workaround and I’m not sure it helps you but it definitely helped me as I had many functions and it was a pain adding all of them to each page.