How to change scope when controller is changed using Angular routes without using $rootScope - angularjs

Question

https://plnkr.co/edit/U9tL95qS5AgsPu6nNwVD/
I am able to change ng-view with templateUrl. But it is not updating {{msg}} when I am updating it using $scope.msg in every new controller.
Is there a way to update it without using $rootscope. Since I have heard that $rootScope practise is bad.
I guess I Am not registering the controller ??
I am new to Angular.
I dont know how to use services
in index.html
app.controller("redCtrl", ['$scope', '$route', function($scope, $route) {
$scope.msg = "I love red"; //NOT WORKING **************
}]);

Answer 1

check out this plnkr https://plnkr.co/edit/rvIZouNydPpwFgsIiVaf
#Rohitas Behera The reason is simple you are using
<div ng-app="myApp" ng-controller="mainController">
<p>Main</p>
Red
Green
Blue
<div ng-view>
</div>
{{msg}} <!-- why using here !>
</div>
so this time the msg is in scope of maincontroller . There are not other controller in scope
To do so remove {{msg}} from index.html and place it in there respective page.
Like this.
blue.html
<div style="background-color:#2196f3;">
<h1>Blue {{msg}}</h1>
</div>
same for all html page.

Answer 2

To alter the value {{msg}} in different context/controller, you will need to write {{msg}} in individual .html files where you have set the scope of respective controller.
As of now the variable is accessible only to your mainController as it is seen in index.html only, hence the value never changes.
You need to remove it from index.html and put it in every html.
here is the fixed plunkr

Answer 3

you have to add {{msg}} in every template.like this
<div style="background-color:#f44336;">
<h1>Red</h1>
{{msg}}
</div>
and remove {{msg}} form index.html page because maincontroller is working for index page and the modified page like this
<div ng-app="myApp" ng-controller="mainController">
<p>Main</p>
Red
Green
Blue
<div ng-view>