promise.js

Function.prototype.promise = function() {
    var method = this;
    var callback;
    var promise = {
        returns: function(method) {
            callback = method;
            return promise;
        }
    };
    method.yield = function() {
        callback.apply(this, arguments);
    }
    return function() {
        method.apply(this, arguments)
        return promise;
    }
}
/* @example */
var example = {
    hello: function hello(name) {
        setTimeout(function(){
            hello.yield("Hello " + name + "!!");
        }, 0);
    }.promise()
}
example.hello("world").returns(function(msg) {
    console.log(msg);
})