async:false option not working in $.ajax() , is it depreciated in jQuery 1.8+ for all use cases?

Question

I'm confused about using the async: false option with $.ajax(). According to the $.ajax() documentation:

As of jQuery 1.8, the use of async: false with jqXHR ($.Deferred) is deprecated; you must use the success/error/complete callback options instead of the corresponding methods of the jqXHR object such as jqXHR.done() or the deprecated jqXHR.success().

I don't know what jqXHR ($.Deferred) means. Is using async:false for any reason depreciated, or is jqXHR ($.Deferred) some sort of special use case?

I ask as I'm having trouble getting an $.ajax() call to happen asynchronously.This is with jQuery 1.8.2:

var ret = {};

$.ajax({
   async:           false,
    method:         'GET',
    contentType:    'application/json',
    dataType:       'jsonp',
    url:            '/couchDBserver',
    error:          myerr,
    success:        function(data) {

        var rows = data.rows;

        //something that takes a long time
        for(var row in rows) {
             ret[rows[row].key] = rows[row].value;
        }

        console.log('tick');
    }
});
console.log('tock');
console.log(JSON.stringify(ret))

My console output is:

tock
{}
tick

Am I doing something wrong, or am I doing something wrong?

Answer 1

what it is saying is, if your request is async: false then you should not use ajax.done(), ajax.fail() etc methods to register the callback methods, instead you need to pass the callback methods using success/error/complete options to the ajax call

correct

$.ajax({
    async: false,
    success: function(){
    },
    error: function(){
    },
    complete: function(){
    }
})

wrong

$.ajax({
    async: false
}).done(function(){
}).fail(function(){
}).always(function(){
})

if async: true //not specified

correct

$.ajax({
}).done(function(){
}).fail(function(){
}).always(function(){
})

or

$.ajax({
    async: false,
    success: function(){
    },
    error: function(){
    },
    complete: function(){
    }
})