JavaScript Variable Scoping in $.getJSON Calls

Question

Why is it that when showOrders gets called the orders array is empty? My service is returning 4 objects and I can walk through the item initialization in the .push call but the array returned is always empty.

var showOrders = function(orders){
    $.each(orders, function(i, val){

        alert(val.Order + "::" + val.Href);         

    });
}
var orders = (function(d){
    var _r = [];
    $.getJSON("/_vti_bin/listdata.svc/Orders", function (data) {
        for(var i = 0; i < data.d.results.length; i++)
        {
            var o = data.d.results[i];

            _r.push({
                    Id: o.Id,
                    Order: o.Order, 
                    PurchaseDate: o.PurchaseDate, 
                    CustomerPO: o.CustomerPO, 
                    PurchasedBy: o.PurchasedBy, 
                    SubTotal: o.SubTotal, 
                    Status: o.Status,
                    Href: o.Path + "/DispForm.aspx?ID=" + o.Id
            });
        }
        return _r;
    });
    d(_r);
})(showOrders);

I think there will be async call so till you get data.. your each function start executing — Pratik Bhatt
– Pratik Bhatt, Commented Feb 1, 2013 at 14:04
This type of question is asked about a 100 times a day. Asynchronous calls can not return back values! It is like making a call to order pizza. You can not eat it until it is delivered. — epascarello
– epascarello, Commented Feb 1, 2013 at 14:18
I think you can see from the use of the delegate I am passing in that it was my intent to call the delegate after the data was retrieved. I just had the call in the wrong line. — jjr2527
– jjr2527, Commented Feb 1, 2013 at 18:56

hereandnow78 · Accepted Answer · 2013-02-01 14:31:06Z

3

$.getJSON is excecuting an async call. you need to excecute the d-callback inside the callback of the getJSON-call (after your loop):

var orders = (function(d){
  var _r = [];
  $.getJSON("/_vti_bin/listdata.svc/Orders", function (data) {
      for(var i = 0; i < data.d.results.length; i++)
      {
          var o = data.d.results[i];

          _r.push({
                Id: o.Id,
                Order: o.Order, 
                PurchaseDate: o.PurchaseDate, 
                CustomerPO: o.CustomerPO, 
                PurchasedBy: o.PurchasedBy, 
                SubTotal: o.SubTotal, 
                Status: o.Status,
                Href: o.Path + "/DispForm.aspx?ID=" + o.Id
        });
      }
      d(_r);

  });

})(showOrders);

answered Feb 1, 2013 at 14:31

hereandnow78

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