The controller with the name 'mainController' is not registered

Question

i have this code in my script.js file

var mainController = function($scope){
  $scope.message = \"Plunker\";
};

and this is my HTML

Answer 1

To paraphrase http://www.w3schools.com/angular/angular_modules.asp

 

{{ firstName + " " + lastName }}


 

The important line is

    app.controller("mainController", function($scope) 

which injects your controller into your app