jQuery Deferred's, $.when() and the fail() callback arguments

Question

I\'m getting an unexpected result when using $.when() when one of the deferred operations does not succeed.

Take this JavaScript, which created 2 deferr

Answer 1

I've faced this same problem, and I dealt with it by using the .always callback and inspecting my array of deferred objects. I had an unknown number of ajax calls, so I had to do the following:

// array of ajax deletes
var deletes = [];
$checkboxes.each(function () {
    deletes.push(deleteFile(this));
});

$.when.apply($, deletes)
  .always(function () {
      // unfortunately .fail shortcircuits and returns the first fail,
      // so we have to loop the deferred objects and see what happened.

      $.each(deletes, function () {
          this.done(function () {
              console.log("done");
          }).fail(function () {
              console.log("fail");
          });
      });
  });

The deleteFile method returns a promise, which has .done or .fail callbacks.

This allows you to take action after all deferreds have completed. In my case I'm going to show a delete file error summary.

I just tried this, and unfortunately I had to put a interval timer to check that they were all truly done after my $.each on the deferred objects. This seems odd and counterintuitive.

Still trying to understand these deferreds!