Question

I have a the following java script object

function eventTypeObj() {

allEventTypes = [];

// When the object is created go and get all the event types that can be included in journey or clusters.
$.ajax({
        url: "/ATOMWebService.svc/GetDisplayEventTypes",
        dataType: "json",
        success: function(result) {
            allEventTypes = eval("(" + result.d + ")");
        }
    });


// Returns a list of all the event type IDS.
this.getEventTypeIds = function() {
    var eventTypeIDs = [];
    for (var i = 0; i < allEventTypes.length; i++) {
        eventTypeIDs.push(allEventTypes[i].Id);
    }
    return eventTypeIDs;
};
}

I was wondering if there is a way stop some one calling the eventTypeObj.getEventTypeIds(); before the ajax call in the constructor has succeeded, and there is no data in the allEventTypes array?

Answer 1

Something like this would be way better (im not guaranteeing this is 100% working, but the concept is sound):

function eventTypeObj() {
    this.allEventTypes = [];
    this.hasLoadedEventTypes = false;

    var loadEventTypes = function(cb) {
        $.ajax({
            url: "/ATOMWebService.svc/GetDisplayEventTypes",
            dataType: "json",
            success: function(result) {
                this.allEventTypes = eval("(" + result.d + ")");
                this.hasLoadedEventTypes = true;
                cb();
            }
        });
    };


    this.getEventTypeIds = function(updateEventTypes, callback) {
        var _getEventTypeIds = function() {
            var eventTypeIDs = [];
            for (var i = 0; i < this.allEventTypes.length; i++) {
                eventTypeIDs.push(this.allEventTypes[i].Id);
            }    
            return eventTypeIDs;
        };


        if (!this.hasLoadedEventTypes || updateEventTypes) {
            loadEventTypes(function(){ callback(_getEventTypeIds()); });
        }
        else callback(_getEventTypeIds());
    };
}

Example usage:

var eto = new eventTypeObj();

eto.getEventTypeIds(false, function(eventTypeIdArray) {
   // do stuff with the id array 
});


/*
    somewhere later on you want to get an updated eventTypeId array
    in case the event types have changed.
*/
eto.getEventTypeIds(true, function(eventTypeIdArray) {
    // do stuff with the updated ids
});