jquery - How to use .promise( ) on a .on( ) event listener? -

i have .on() listener 'fetch' event. there easy way can fire event when finishes?

      this.on('fetch', function() {            log('fetch event started!!');        });         // fetch event ended??? 

i have been playing around .promise() not getting results.

update - here code tapping fetch event collection can show/hide loading icons , other work.

   var tweetlist = backbone.collection.extend({             model: tweetmodel,             // used collection.sort()              comparator: function (item) {                 return item.get("createddate");             },             initialize: function(models, options) {                 this.on('fetch', function() {                     console.log('fetch event started!!');                  });              },             fetch: function(options) {                 this.trigger('fetch', this, options);                 return backbone.collection.prototype.fetch.call(this, options);             }         }); 

i tried binding event fetch doesn't it's firing correctly.

 var tweetlist = backbone.collection.extend({             model: tweetmodel,             // used collection.sort()              comparator: function (item) {                 return item.get("sortorder");             },             initialize: function(models, options) {                 this.on('fetch', function(m, o) {                     log(o.status);                  });              },             fetch: function(options) {                 this.trigger('fetch', this, { status: "started"});                 this.trigger('fetch', this, { status: "ended"});                 return backbone.collection.prototype.fetch.call(this, options);             }         }); 

using q (https://github.com/kriskowal/q) , jquery potentially...

this.on('fetch', function() {            console.log('fetch event started!!');         q($.ajax(...)).then(function () {             console.log("fetch event ended...");         });        }); 

alternatively, here's example using jquery...

this.on('fetch', function() {     console.log('fetch event started!!');     $.when( $.ajax(...) ).then(function( data, textstatus, jqxhr ) {         console.log('fetch event ended...');     }); });