Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<div ng-controller="MyCtrl">
    <div 
    data-ng-class="{
        'bold-selected': option.id == selectedId
       }"
    data-ng-repeat="option in data" 
    data-ng-click="addClassToSelected(option.id)"
    id="1_{{ data.id }}">div1</div>
</div>

CSS

.bold-selected {
    font-weight: bold;
}

JavaScript

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

//myApp.directive('myDirective', function() {});
//myApp.factory('myService', function() {});

function MyCtrl($scope) {
    $scope.data = [{ id: 1 },{ id: 2 },{ id: 3 },{ id: 4 },{ id: 5 },{ id: 6 },{ id: 7 }];
    $scope.selectedId = false;
    $scope.addClassToSelected = function(id){
        $scope.selectedId = id;
    }
}