Add the ability to pass a context reference through to visitor interface callbacks...

[ChrisRus]

Developers are currently forced to manage any context their visitor interfaces require above and beyond the context provided by the request object passed to each callback by the algorithm. Typically, developers leverage a JavaScript closure scope and define their visitor object and invocation of the jsgraph algorithm in that scope.

For example, it is typical that visitor interface function implementations record information that is required in part or in whole to produce the result of the operation. Currently, it is assumed that developers will take care of this detail on their own.

cycleEdges = [];
var dftVisitor = {
    forwardOrCrossEdge: function(request) {
        cyclesEdges.push(request.e); // record the edge
        // What I want is rather: request.context.cyclesEdges.push(request.e);
       return true; // continue the traversal
    }
};
var response = jsgraph.directed.depthFirstTraverse({ digraph: digraph, visitor: dftVisitor });
if (response.error) {
    throw new Error(response.error); // e.g.
}
if (cycleEdges.length) {
    console.log("Digraph contains cycles on the following edges: " + JSON.stringify(cycleEdges) );
}

'''

However, in more advanced scenarios it would be helpful to have a standard way to direct visitor interfaces to a specific sandbox for keeping track of intermediate state and building results.

Make it possible to pass a context reference via traversal algorithm request object that gets passed to visitor callbacks. This will allow the algorithm caller far more flexibility and control than is now convenient.

[ChrisRus]

Nice to have but not critical enough to invest the time to test the solution right now.