Binding CSS classes using ng-class AngularJS 1.4.x

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

app.controller('MainCtrl', function($scope) {
	      $scope.value = 1;
		    $scope.isBold = function () { return $scope.value % 2 === 0; };
        $scope.isItalic = function () { return $scope.value % 3 === 0; };
        $scope.isUnderlined = function () { return $scope.value % 5 === 0; };
});

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

  <head>
    <meta charset="utf-8" />
    <title>AngularJS Plunker</title>
    <script>document.write('<base href="' + document.location + '" />');</script>
    <link rel="stylesheet" href="style.css" />
    <script data-require="angular.js@1.4.x" src="https://code.angularjs.org/1.4.3/angular.js" data-semver="1.4.3"></script>
    <script src="app.js"></script>
  </head>

  <body ng-controller="MainCtrl">
  <input type="text" ng-model="value" />
  <span ng-class="{bold: isBold(), italic: isItalic(), underline: isUnderlined()}">
  Example Text</span>

  </body>

</html>

/* Put your css in here */
.bold {
 font-weight:bold;
}
.italic {
font-style:italic;
}
.underline {
    text-decoration: underline;
}