I'm developing FutureJS which was originally based on Crockford's promises (original slides). The current goal is to be the Async Toolbox of JavaScript and eliminate chaining clutter.
Futures.chainify(providers, consumers, context, params)
Asynchronous method queueing allows you to chain actions on data which may or may not be readily available.
This is how Twitter's @Anywhere api works.
You might want a model which remotely fetches data in this fashion:
Contacts.all(params).randomize().limit(10).display();
Contacts.one(id, params).display();
Which could be implemented like so:
var Contacts = Futures.chainify({
// Providers must be promisables
all: function(params) {
var p = Futures.promise();
$.ajaxSetup({ error: p.smash });
$.getJSON('http://graph.facebook.com/me/friends', params, p.fulfill);
$.ajaxSetup({ error: undefined });
return p.passable();
},
one: function(id, params) {
var p = Futures.promise();
$.ajaxSetup({ error: p.smash });
$.getJSON('http://graph.facebook.com/' + id, params, p.fulfill);
$.ajaxSetup({ error: undefined });
return p.passable();
}
},{
// Consumers will be called in synchronous order
// with the `lastResult` of the previous provider or consumer.
// They should return either lastResult or a promise
randomize: function(data, params) {
data.sort(function(){ return Math.round(Math.random())-0.5); // Underscore.js
return Futures.promise(data); // Promise rename to `immediate`
},
limit: function(data, n, params) {
data = data.first(n);
return Futures.promise(data);
},
display: function(data, params) {
$('#friend-area').render(directive, data); // jQuery+PURE
// always return the data, even if you don't modify it!
// otherwise your results could be unexpected
return data;
}
});
Things to know:
providers - promisables which return dataconsumers - functions which use and or change data
- the first argument must be
data
- when returning a promisable the next method in the chain will not execute until the promise is fulfilled
- when returning a "literal object" the next method in the chain will use that object
- when returning
undefined (or not returning anything) the next method in the chain will use the defined object
context - apply()d to each provider and consumer, thus becoming the this objectparams - reserved for future use
Alternatively you could use synchronous callback chaining - what you may have seen elsewhere as chain().next() or then():
Futures.sequence(function(callback) {
$.getJSON("http://example.com", {}, callback);
}).then(function(callback, result, i, arr) {
var data = transform_result(result);
$.getJSON("http://example.com", data, callback);
}).then(...)
I named it sequence rather than chain since _.js already has a method named chain and I'd like to use _.methodName for my library as well.
Take a peek and let me know what you think.
FuturesJS will work alongside jQuery, Dojo, etc without issue. There are no dependencies. It will work with Node.js (and Rhino when using env.js).
=8^D
P.S. As to the ORM / MVC fix - you can check out JavaScriptMVC and SproutCore. I'm also working on my own solution called TriforceJS, but I don't have anything ready for release yet.
P.P.S Example of promisables
var doStuff = function (httpResult) {
// do stuff
},
doMoreStuff = function (httpResult) {
// do more stuff
};
function fetchRemoteData(params) {
var promise = Futures.promise();
$.getJSON("www.example.com", params, promise.fulfill, 'jsonp');
return promise;
}
p = fetchRemoteData(params);
p.when(doStuff);
p.when(doMoreStuff);
