What comes first .always() or .then() callbacks in jQuery? [duplicate]

Question

If you have a function which has both .then and .always callbacks, which one will get executed first?

Janik

Why don't you just try it and see, I'm guessing then() – Devonadevondra

And I just did, took one minute, and I was right -> jsfiddle.net/adeneo/ou1sy6uw – Devonadevondra

However, swapping them, they return differently -> jsfiddle.net/adeneo/ou1sy6uw/1, so whatever order they are added – Devonadevondra

The best would be to not rely on the order. Single threaded JS by default is protected from concurrency issues, if only we don't do silly things in our code. – Adelia

OP, please rephrase your title to be more specific... – Herculean

Answer 1

Taken from the deferred.resolve() documentation:

When the Deferred is resolved, any doneCallbacks added by deferred.then() or deferred.done() are called. Callbacks are executed in the order they were added.

Example below:

var $logger = $("#logEntry");
function addLog(content){
   $logger.append($("<li/>").html(content));
}

var newPromise = $.Deferred();

$.when(newPromise).done(function() {
    addLog("1st $when().done!");
});

newPromise.then(function() {
    addLog("1st then!");
}).always(function() {
    addLog("1st always!");
}).done(function() {
    addLog("1st done!");
}).done(function() {
    addLog("2nd done!");
}).always(function() {
    addLog("2nd always!");
}).then(function() {
    addLog("2nd then!");
});

$.when(newPromise).done(function() {
    addLog("2nd $when().done!");
});

addLog("Resolving promise!");

newPromise.resolve();

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<ul id="logEntry"></ul>

Nga

In your example always is attached to then, which is a bit different from what OP asked. – Adelia