allow number only in angularjs

 $scope.allowNumberOnly = function ($event) {
            var a = [];
            var k = $event.which;
            for (var i = 48; i < 58; i++)
                a.push(i);
            if (k === 46 || k === 8) {
                a.push(k);
            }
            if (!(a.indexOf(k) >= 1))
                $event.preventDefault();
        };