copying the co idea but supporting only yielding thunks. run with node >= 0.11.2: `node --harmony myCoExperiment.js`

myCoExperiment.js

'use strict';

/*jshint esnext:true */



let log = function(msg) { console.log(msg); };
let now = function() { return Date.now(); };



// emulating co
let co = function(fn) {
    let it = fn();

    var cycle = function(loop) {
        let running = loop;
        let runOnce = !loop;
        let out;

        //log('cycle started with loop: ' + loop);

        while (running || runOnce) {
            runOnce = false;
            out = it.next(); 

            if (out && 'done' in out && 'value' in out) {
                if (out.done) {
                    running = false;
                    //log('done - stopping cycle due to done');
                }
                else if (typeof out.value === 'function') {
                    running = false;
                    //log('done - stopping cycle due to value being a function (assuming it is a thunk!)');
                    out.value(cycle);
                }
                else {
                    running = true;
                    //log('got other stuff: ' + out.value);
                }
            }
        }
    };

    cycle(true);
};



// like co-sleep
let sleep = function(ms) {
    return function(cb) {
        setTimeout(cb, ms);
    };
};



co(function *() {
    log('1) ' + now());
   
    yield sleep(1000);
    log('2) ' + now());

    yield sleep(1000);
    log('3) ' + now());

    yield 2;
    log('DONE!');
});