Angular: Empty Fiddle

http://angularjs.org/

HTML

<script src="http://code.angularjs.org/angular-1.0.1.js"></script>
<div ng-controller="MyCtrl">
    {{ colour }}
</div>

JavaScript

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

angular.module('myApp').filter('getColour', getColour);

function getColour() {
    return filter;

    function filter(object, key) {
        var colour;
        angular.forEach(object, function(set) {
            if (set.key === key)
                colour = set.color;
        });

        return colour;
    }
}

function MyCtrl($scope, $filter) {
    var myobj = {
        "set1": {
            "key": "B11",
            "color": "yellow"
        },
        "setA": {
            "key": "F34",
            "color": "green"
        }
    }

    $scope.colour = $filter('getColour')(myobj, 'F34');
}