Untitled

<!DOCTYPE html>
<html ng-app="myApp">

  <head>
    <script data-require="angular.js@1.3.17" data-semver="1.3.17" src="https://code.angularjs.org/1.3.17/angular.js"></script>
    <link rel="stylesheet" href="style.css" />
    <script src="script.js"></script>
  </head>

  <body ng-controller="myCtrl">
    <button type="submit" class="btn btn-primary" ng-class="{disableSaveCls:disableSubmitButton}" ng-click="submitClicked()">Submit</button>
  </body>

</html>

// Code goes here

var myApp = angular.module('myApp', []);

myApp.controller('myCtrl', function($scope) {
  $scope.disableSubmitButton = false;
  
  $scope.submitClicked = function() {
    $scope.disableSubmitButton = !$scope.disableSubmitButton;
  }
});

/* Styles go here */

.disableSaveCls {
  background: red;
}