Za: https://medium.com/@munawwar/fresh-new-look-at-callbacks-1e2abf693102#.lk0tk2w44
//synchronously mode action3(action2(action1())); //or if the operation is chainable action1().action2().action3(); //more sophisticated example (in other usage) var res = action1(); res = (res ? action2() : action3()); action4(res);