meh, fork + join.. sort of

fork-join.js

console.clear();

var node = {
    first: function() {
        console.log(this.hello);
        this.hello++;
    },
    second : function() {
        console.log(this.hello);
        this.hello+=100;
    },
    merge  : function(first,second) {
        console.log("merged: " + (first.hello + second.hello));
    }
};

var fork = function(handler) {
   var scope = {
        hello : 0,
        run   : function() {
            handler.call(scope);
            console.log("now:" + scope.hello);
        }
   };
   return scope;
};

var join = function(firstHandle, secondHandle, cb) {
   var scope = {
       first  : [firstHandle],
       second : [secondHandle] 
   };

   var ret = function(handle) {
        
       if (handle === scope.first[0]) {
           scope.first.push(handle);
       } else if (handle === scope.second[0]) {
           scope.second.push(handle);
       }
 
       if (scope.first.length === 2 && scope.second.length === 2) {
           cb.call(scope, scope.first[0], scope.second[0]);
       }
       return ret;
   };
   return ret;
};



var firstHandle = fork(node.first);
var secondHandle = fork(node.second);

firstHandle.run();
firstHandle.run();
firstHandle.run();
join(firstHandle,secondHandle, node.merge)(secondHandle)(firstHandle);
secondHandle.run();
secondHandle.run();
secondHandle.run();

join(firstHandle,secondHandle, node.merge)(secondHandle)(firstHandle);