Pass a variable to a function from inside an ajax call

Question

I tried to use this loop to read some urls to read their modified time:

var arr = [];

//... fill arr with push

for (var e in arr) {
        nodename=arr[e].hos         


        

Answer 1

your are directly executing the method and passing its result as the callback for the success callback.

the xhr is already passed as the 3rd argument so try

success: function(nn,status, xhr) {
            $('#host_'+nn).append("last modified: " + xhr.getResponseHeader("Last-Modified"));
        }

---

if you have to pass the nodename as well, the you need to use a function that returns a function

success: (function(nn){
              return function(data ,status, xhr) {
                 // you can use nodename here...
                 $('#host_'+nn).append("last modified: " + xhr.getResponseHeader("Last-Modified"));
            };
        })(nodename)

Answer 2

If arr is truly an array, just use .forEach or even better .map (with a shim on older browsers) to encapsulate each iteration's scope without the need for additional closures:

var xhrs = arr.map(function(e) {
    var nodename = e.hostname;
    var node_json = "/nodes/" + nodename;

    html +='<a href="'+node_json+'" target="_blank" id="host_'+nodename+'">data</a>';

    return $.ajax({
        url: node_json
    }).done(function(data, status, xhr) {
        $('#host_'+nodename).append("last modified: " + xhr.getResponseHeader("Last-Modified"));
    });
});

The reason to use var xhrs = arr.map() instead of .forEach is that you then (for free) get the ability to call yet another callback once every AJAX request has completed:

$.when.apply($, xhrs).then(function() {
     // woot!  They all finished
     ...
});