Difference between $scope and $rootScope

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In this video we will discuss the difference between $scope and $rootScope. The main difference is that, $rootScope is available globally (for all controllers), whereas $scope is only available to the controller that has created it and it's children.



Let us understand this with an example.

Controller Code : We have 2 controllers (redColourController & greenColourController). redColourController has set redColour property on $scope and rootScopeColour on $rootScope. This means redColour property cannot be used outside the redColourController, where as rootScopeColour that is set on $rootScope can be used anywhere. greenColourController has set greenColour property on $scope. This means greenColour property cannot be used outside the greenColourController

var app = angular

            .module("Demo", [])

            .controller("redColourController", function ($scope, $rootScope) {

                $rootScope.rootScopeColour = "I am Root Scope Colour";

                $scope.redColour = "I am Red Colour";

            })

            .controller("greenColourController", function ($scope) {

                $scope.greenColour = "I am Green Colour";

            })

View HTML : 

<div ng-controller="redColourController">

    Root Scope Colour : {{rootScopeColour}} <br />

    Red Colour Controller : {{redColour}} <br />

    Green Colour Controller :

    <span style="color:red" ng-show="greenColour == undefined">

        greenColour is undefined

    </span>

</div>

<br />

<div ng-controller="greenColourController">

    Root Scope Colour : {{rootScopeColour}} <br />

    Green Colour Controller : {{greenColour}} <br />

    Red Colour Controller :

    <span style="color:red" ng-show="redColour == undefined">

        redColour is undefined

    </span>

</div>

Output : From the output it is clear that the rootScopeColour property that is set on $rootScope is available for both the controllers (redColourController & greenColourController). Where as redColour property set on $scope is available only for redColourController and not for greenColourController. Similarly, greenColour property set $scope is available only for greenColourController and not redColourController. Hope this example has made the difference between $rootScope and $scope clear.