repejota/index.html

## index.html
<body>
    <div class="container" ng-controller="TestCrtl">
         <h1>AngularJS array sum by field/key filter example</h1>
        <table class="table table-bordered table-condensed">
            <thead>
                <tr>
                    <th>Name</th>
                    <th>Posts</th>
                    <th>Comments</th>
                </tr>
            </thead>
            <tbody>
                <tr ng-repeat="user in users">
                    <td>{{user.name}}</td>
                    <td>{{user.posts}}</td>
                    <td>{{user.comments}}</td>
                </tr>
            </tbody>
            <tfoot>
                <tr>
                    <th></th>
                    <th>{{users|sumByKey:'posts'}}</th>
                    <th>{{users|sumByKey:'comments'}}</th>
                </tr>
            </tfoot>
        </table>
    </div>
</body>

## index.js
angular.module('exampleFilter', [])
    .filter('sumByKey', function () {
    return function (data, key) {
        if (typeof (data) === 'undefined' || typeof (key) === 'undefined') {
            return 0;
        }

        var sum = 0;
        for (var i = data.length - 1; i >= 0; i--) {
            sum += parseInt(data[i][key]);
        }

        return sum;
    };
})
    .controller('TestCrtl', function ($scope) {
    $scope.users = [{
        name: 'Kenny',
        posts: 1,
        comments: 6
    }, {
        name: 'Kyle',
        posts: 2,
        comments: 7
    }, {
        name: 'Eric',
        posts: 3,
        comments: 8
    }, {
        name: 'Stan',
        posts: 4,
        comments: 9
    }, {
        name: 'Butters',
        posts: 5,
        comments: 10
    }, ];
});
	<body>
	<div class="container" ng-controller="TestCrtl">
	<h1>AngularJS array sum by field/key filter example</h1>
	<table class="table table-bordered table-condensed">
	<thead>
	<tr>
	<th>Name</th>
	<th>Posts</th>
	<th>Comments</th>
	</tr>
	</thead>
	<tbody>
	<tr ng-repeat="user in users">
	<td>{{user.name}}</td>
	<td>{{user.posts}}</td>
	<td>{{user.comments}}</td>
	</tr>
	</tbody>
	<tfoot>
	<tr>
	<th></th>
	<th>{{users\|sumByKey:'posts'}}</th>
	<th>{{users\|sumByKey:'comments'}}</th>
	</tr>
	</tfoot>
	</table>
	</div>
	</body>
	angular.module('exampleFilter', [])
	.filter('sumByKey', function () {
	return function (data, key) {
	if (typeof (data) === 'undefined' \|\| typeof (key) === 'undefined') {
	return 0;
	}

	var sum = 0;
	for (var i = data.length - 1; i >= 0; i--) {
	sum += parseInt(data[i][key]);
	}

	return sum;
	};
	})
	.controller('TestCrtl', function ($scope) {
	$scope.users = [{
	name: 'Kenny',
	posts: 1,
	comments: 6
	}, {
	name: 'Kyle',
	posts: 2,
	comments: 7
	}, {
	name: 'Eric',
	posts: 3,
	comments: 8
	}, {
	name: 'Stan',
	posts: 4,
	comments: 9
	}, {
	name: 'Butters',
	posts: 5,
	comments: 10
	}, ];
	});