@Eselk, In my experience, the $.Deferred(function(def) {…}); construction is rarely needed, though I guess it can be quite useful in some circumstances. Firstly, : return $.Deferred(function(def) { def.resolve(); }).promise(); will simplify to : return $.Deferred().resolve().promise(); Secondly, in DataService.makeRequest() you can avoid the need for an explicit $.Deferred by exploiting .then(), as follows : function DataService() … Read more
Depending on your use case, you could also use jQuery.when [1]: If a single argument is passed to jQuery.when and it is not a Deferred, it will be treated as a resolved Deferred and any doneCallbacks attached will be executed immediately. With jQuery.when you can treat your mysterious object always as deferred: // x could … Read more
Promises also rely on callbacks behind the scene, so it’s not really one vs. the other. The benefit of callbacks is that they are easy to implement with plain JavaScript (for example in ajax calls). Promises require an additional abstraction layer, which usually means that you’ll rely on a library (not an issue in your … Read more
You can use .when(), and .apply() with multiple deferred. Extremely useful: function updateAllNotes() { var getarray = [], i, len; for (i = 0, len = data.length; i < len; i += 1) { getarray.push(getNote(data[i].key)); }; $.when.apply($, getarray).done(function() { // do things that need to wait until ALL gets are done }); }
I’m a bit confused by this question. I think this is because you are confused by promise and delegate. They are in fact completely unrelated features of jQuery. I’ll explain each separately: delegate delegate is a feature of jQuery that was introduced in jQuery 1.4.2. (It is a nicer approach to the live feature that … Read more
function showData(data1, data2) { alert(data1[0].max_id); alert(data2[0].max_id); } function method1() { return $.ajax(“http://search.twitter.com/search.json”, { data: { q: ‘ashishnjain’ }, dataType: ‘jsonp’ }); } function method2() { return $.ajax(“http://search.twitter.com/search.json”, { data: { q: ‘ashishnjain’ }, dataType: ‘jsonp’ }); } $.when(method1(), method2()).then(showData); Here’s a working jsFiddle
First: You cannot use $.Promise(); because it does not exist. A deferred object is an object that can create a promise and change its state to resolved or rejected. Deferreds are typically used if you write your own function and want to provide a promise to the calling code. You are the producer of the … Read more
There are two ways to handle this, and which you choose depends on which component should own the data and the loading state. Move the Ajax request into the parent and conditionally render the component: var Parent = React.createClass({ getInitialState: function() { return { data: null }; }, componentDidMount: function() { $.get(‘http://foobar.io/api/v1/listings/categories/’).done(function(data) { this.setState({data: data}); … Read more
Since jQuery 1.8 .then behaves the same as .pipe: Deprecation Notice: As of jQuery 1.8, the deferred.pipe() method is deprecated. The deferred.then() method, which replaces it, should be used instead. and As of jQuery 1.8, the deferred.then() method returns a new promise that can filter the status and values of a deferred through a function, … Read more
success only fires if the AJAX call is successful, i.e. ultimately returns a HTTP 200 status. error fires if it fails and complete when the request finishes, regardless of success. In jQuery 1.8 on the jqXHR object (returned by $.ajax) success was replaced with done, error with fail and complete with always. However you should … Read more