gistfile1.txt

//Attempt up to 5 ports, so 8000, 8001, 8002, 8003, 8004.
setupHTTPServer(5);

function setupHTTPServer(max, count){
    count = (count === undefined) ? 0 : count;
    
    //The 2nd parameter means we only listen to local connections
    var server = app.listen(8000+count, "127.0.0.1", function (err) {
        if (server.address()){
            console.log('Listening on port "+server.address().port);
        }
    });
    
    //If a EADDRINUSE error gets raised, try the next port. If one of them is successful, we're good to go.
    server.on("error", function (err){
        server.removeListener("error", function (){}); // Always remove listeners!
        
        if (count < max-1) {
            //Attempt again, recursion strategy.
            setupHTTPServer(max, count+1);
        }else{
            //It seems like we already have every port listened to. We don't need this process, so lets exit.
            process.exit();
        }
    });
}