Super simple implementation of something like co

colike.js

function colike(genFunc) {
  var gen = genFunc();
  var thunk = gen.next().value;

  function done() {
    // We don't know the number of arguments.
    var err = arguments[0];
    var values = Array.prototype.slice.call(arguments, 1);

    if (err) {
      gen.throw(err);
      return;
    }

    console.log('values', values);

    var result = gen.next(values);
    if (result.done) {
      console.log('Done!');
    } else {
      console.log('More yields are waiting!');
      thunk = result.value;
      thunk(done);
    }
  }

  thunk(done);
}

test.js

var colike = require('./colike');

colike(function *() {
  var a = yield function(callback) {
    setTimeout(function() {
      callback(null, 1, 2, 3);
    }, 100);
  };
  console.log('a', a);
  var b = yield function(callback) {
    setTimeout(function() {
      callback(null, 'hello', 'world');
    }, 100);
  };
  console.log('b', b);
  var c = yield function(callback) {
    setTimeout(function() {
      callback(new Error('errrrrrrrrror'));
    }, 100);
  }
});