naive_promises

    var log = function log (e) {
        console.log(e);
    };

    var Promise = function () {
        this.resolved = false;
        this.resolvedValue = null;
        this.rejected = false;
        this.rejectedValue = null;
    };
    Promise.prototype.then = function (okCb, errCb) {
        this.okCb = okCb;
        this.errCb = okCb;
        this.nextPromise = new Promise();
        if (this.resolved || this.rejected) {
            this._fulfill();
        }
        return this.nextPromise;
    };

    Promise.prototype._fulfill = function () {
        var val = this.resolved ? this.resolvedValue : this.rejectedValue;
        var func = this.resolved ? this.okCb : this.errCb || log;
        var that = this;
        setTimeout(function () {
            try {
                var result = func(val);
                if (result.then) {
                    result.then(function (val) {
                        that.nextPromise.resolve(result);
                    }, function (e) {
                        that.nextPromise.reject(result);
                    });
                } else {
                    that.nextPromise.resolve(result);
                }
            } catch(e) {
                that.nextPromise.reject(e);
            }
        }, 0);
    };

    Promise.prototype.resolve = function (val) {
        this.resolved = true;
        this.resolvedValue = val;
        if (this.okCb) {
            this._fulfill();
        }
    };

    Promise.prototype.reject = function (val) {
        this.rejected = true;
        this.rejectedValue = val;
        if (this.okCb) {
            this._fulfill();
        }
    };

    Promise.prototype.done = function () {
        if (this.rejected) {
            throw this.rejectedValue;
        }
    };


    var Deferred = function () {
        this.promise = new Promise();
    };

    Deferred.prototype.resolve = function (val) {
        this.promise.resolve(val);
    };

    Deferred.prototype.reject = function (val) {
        this.promise.reject(val);
    };

    var Q = {
        defer: function () {
            return new Deferred();
        }
    };