Question

I have web methods that are called via AJAX in a .Net 4.0 web app. In many cases, the AJAX calls are made repeatedly in a for loop. My problem is, the information the web method is syncing to my server is time stamped and therefore must be synced in the order in which I am sending it to AJAX. Unfortunately, it seems whatever finishes first, simply finishes first and the time stamps are all out of order. I need to basically queue up my AJAX requests so that they execute in order rather than Asynchronously, which I know is the A in AJAX so this might be a totally dumb question.

How do I force the order of execution for AJAX calls done in a for loop?

Edit: Some code

                    for (var i = 0; i < itemCnt - 1; i++) {

                    try {
                        key = items[i];
                        item = localStorage.getItem(key);
                        vals = item.split(",");
                        type = getType(key);


                        if (type == "Status") {
                            var Call = key.substring(7, 17);
                            var OldStat = vals[0];
                            var NewStat = vals[1];
                            var Date1 = vals[2];
                            var Time1 = vals[3];
                            var miles = vals[4];

                            try {
                                stat(Call, OldStat, NewStat, Date1, Time1, miles, key);

                            }
                            catch (e) {
                                alert("Status " + e);
                                return;
                            }

                        }
                        else if (type == "Notes") {
                            var Call = key.substring(6, 16);
                            var Notes = item;
                            try {
                                addNotes(Call, Notes);
                            }
                            catch (e) {
                                alert("Notes " + e);
                                return;
                            }
                        }
                        else if (key == "StartNCTime" || key == "EndNCTime") {
                            var TechID = vals[0];
                            var Date = vals[1];
                            var Time = vals[2];
                            var Activity = vals[3];
                            var Location = vals[4];
                            var Type = vals[5];

                            try {
                                logTime(TechID, Date, Time, Activity, Location, Type, 
                            }
                            catch (e) {
                                alert(key + ' ' + e);
                                return;
                            }

                        }
                    }
                    catch (e) {
                        alert(key + ' ' + e);
                        return;
                    }
                }

function stat(Call, OldStat, NewStat, Date1, Time1, miles, key) {
$.ajax({
    type: "POST",
    dataType: "json",
    contentType: "application/json",
    url: "Service.asmx/update_Stat",
    data: '{ CallNumber:"' + Call + '", OldStat:"' + OldStat + '", NewStat:"' + NewStat + '", Date1:"' + Date1 + '", Time1:"' + Time1 + '", Miles: "' + miles + '"}',
    success: function (data) { },
    error: function (xhr, status, error) {
        var err = eval("(" + xhr.responseText + ")");
        alert("Sync Update Stat: " + err.Message);
        location = location;
    }
});
}

function logTime(TechID, Date, Time, Activity, Location, Type, key) {
$.ajax({
    type: "POST",
    dataType: "json",
    contentType: "application/json",
    url: "Service.asmx/nonCallTime",
    data: '{ TechID:"' + TechID + '", Date1:"' + Date + '", Time1:"' + Time + '", Activity:"' + Activity + '", Location:"' + Location + '", Type: "' + Type + '"}',
    success: function (data) { },
    error: function (xhr, status, error) {
        var err = eval("(" + xhr.responseText + ")");
        alert("Sync Non Call Time: " + err.Message);
        location = location;
    }
});
}

function addNotes(Call, Notes) {
$.ajax({
    type: "POST",
    dataType: "json",
    contentType: "application/json",
    url: "Service.asmx/addNote",
    data: '{ Call:"' + Call + '", Notes:"' + Notes + '"}',
    success: function (data) { },
    error: function (xhr, status, error) {
        var err = eval("(" + xhr.responseText + ")");
        alert("Sync Notes: " + err.Message);
        location = location;
    }
});

}

Answer 1

You have to use callbacks.

function ajax1(){
   //..some code
   //on ajax success:
   ajax2();
}

//etcetera...

Or might I suggest using a javascript library like jQuery to synchronize your ajax requests for you.