AngularJS Live Example

HTML

<div ng-app="app">
  <div ng-controller="test">
    <li ng-repeat="item in data" make-blue="$index === 0">
      {{item}}
      </li>
  </div>
</div>

CSS

.blue {
    color: blue;
}

JavaScript

angular.module('app', [])
.controller('test', function ($scope) {
    $scope.data = [1,2,3,4];
})
    .directive('makeBlue', function () {
        return {
            scope: { 
                makeBlue: '='
            },
            link: function(scope, element, attr) {
                console.log("make ", scope.makeBlue);
                if (scope.makeBlue)
                   element.addClass('blue');
            }

        }
    })