function TopologicalSorter() {
    var graph = {},
        isVisitedNode,
        finishTimeCount,
        finishingTimeList,
        nextNode;

    this.addOrder = function (nodeA, nodeB) {
        nodeA = String(nodeA);
        nodeB = String(nodeB);
        graph[nodeA] = graph[nodeA] || [];
        graph[nodeA].push(nodeB);
    }
    
    this.sortAndGetOrderedItems = function () {
        isVisitedNode = Object.create(null);
        finishTimeCount = 0;
        finishingTimeList = [];

        for (var node in graph) {
            if (graph.hasOwnProperty(node) && !isVisitedNode[node]) {
                dfsTraverse(node);
            }
        }

        finishingTimeList.sort(function (item1, item2) {
            return item1.finishTime > item2.finishTime ? -1 : 1;
        });

        return finishingTimeList.map(function (value) { return value.node })
    }

    function dfsTraverse(node) {
        isVisitedNode[node] = true;
        if (graph[node]) {
            for (var i = 0; i < graph[node].length; i++) {
                nextNode = graph[node][i];
                if (isVisitedNode[nextNode]) continue;
                dfsTraverse(nextNode);
            }
        }

        finishingTimeList.push({
            node: node,
            finishTime: ++finishTimeCount
        });
    }
}


/* TEST */
var topoSorter = new TopologicalSorter();
topoSorter.addOrder(5, 2);
topoSorter.addOrder(5, 0);
topoSorter.addOrder(4, 0);
topoSorter.addOrder(4, 1);
topoSorter.addOrder(2, 3);
topoSorter.addOrder(3, 1);
console.log(topoSorter.sortAndGetOrderedItems());