perform code once all ajax requests are completed

Question

I've got quite a complex search which utilises multiple ajax calls, the flow is as follows:

user performs search on button click
ajax request is made to php page which returns json data
    for each result in returned data additional ajax request is made
        run function which makes additional ajax call
    end for each
end click function

this all works nicely, what i would like to do is display a loading message in a div and disable the search button, then when all the ajax requests have completed re-enable the button and remove the loading message.

my script is below, at the moment the disable/renable of the button is happening almost instantaneously, i presume because the ajax calls are asyncronus, how do i go about renabling the button and removing the loading message once all the ajax requests have completed and displayed the data??

$('#advKeyBtn').live('click', function() {
        $('#advKeyBtn').attr('disabled', 'disabled');
        $('#searchStatus').html('<img src="../img/icons/loadinfo.gif" width="16" height="16" /> Searching Locations...');
        $('#results').html(''); //clear existing contents
        $('#borough_links').html(''); //clear existing contents
        // handler for advance search button
        var myUrl = 'getKeyBoroughs.php';
        var myKeys = $('#keywords').val();
        var myType = $('input[name=keyParams]:checked').val()       
        $.ajax({
            url: myUrl,
            data: "keys=" + myKeys +'&type='+myType,
            type: "POST",
            traditional: false,
            dataType: 'json',
            error: function(xhr, statusText, errorThrown){
                // Work out what the error was and display the appropriate message
            },
            success: function(myData){
                // data retrived ok
                $.each(myData.boroughs, function( intIndex, objValue ){
                    //alert(myData.boroughs[intIndex].Borough_ID);
                    makeCSS(myData.boroughs[intIndex].Borough_ID);


    getKeyLocations(myData.boroughs[intIndex].Borough_ID)
                    })
                    //$('#'+divId).append(myData)//construct location holders
                }
            });
            $('#advKeyBtn').attr('disabled', '');
            $('#searchStatus').html('Search Complete, click on an area to view locations');
        });

and the function that gets called from the initial success of the main ajax call

function getKeyLocations(id){
                    var myUrl = 'getKeyLocations.php';
                    var myBorough = id;
                    var myKeys = $('#keywords').val();
                    var myType = $('input[name=keyParams]:checked').val()   
                    var divId = '#borough_'+ id;
                    $.ajax({
                        url: myUrl,
                        type: 'POST',
                        data: 'borough_id='+myBorough+'&keys='+myKeys,
                        error: function(xhr, statusText, errorThrown){
                            // Work out what the error was and display the appropriate message
                        },
                        success: function(myData){
                            $(divId).html(myData);
                        }
                    });
                };

Answer 1

You have to create a function that will handle all your requests. When all requests are finished then enable the button and show the message.

var ajaxLoading = {
        _requestsInProcess: 0,

        show: function () {
            if (this._requestsInProcess == 0) {
                $('#advKeyBtn').attr('disabled', 'disabled');
                $('#searchStatus').html('<img src="../img/icons/loadinfo.gif" width="16" height="16" /> Searching Locations...');
            }

            this._requestsInProcess++;
        },

        hide: function () {
            this._requestsInProcess--;
            if (this._requestsInProcess == 0) {
                $('#advKeyBtn').attr('disabled', '');
                $('#searchStatus').html('Search Complete, click on an area to view locations');
            }
        }
    };

now, before all ajax call use:

ajaxLoading.show()

And in all your success methods use:

ajaxLoading.hide()

Hope this helps.