javascript - Safari: After 6 concurrent XMLHttpRequest requests, progress block won't get called -

i building multiple file upload jquery script, , using xmlhttprequest , formdata upload files. works great.

but, testing , have read, can have 6 concurrent xmlhttprequest requests @ same time. testing correct, after of 6 complete, next ones in queue upload, 1 expect.

the issue arises progress function. function getting called first 6 files when using safari, next files queued not call progress method. firefox , chrome perform correctly , show progress files. here using:

_makerequest: function(asset) {     var _this = this;     var xhr = new xmlhttprequest();     (function(progress) {          xhr.upload.onprogress = function(e) {             if (e.lengthcomputable) {                 _this._progress(asset, e);             } else {                 _this._log('error: 'asset.file.name+' not computable');             }         };     }(asset.progress));     xhr.upload.addeventlistener('load', function(e) {         _this._complete(e, _this);     });     xhr.upload.addeventlistener('error', function(e) {         _this._failed(e, _this);     });     xhr.upload.addeventlistener("abort", function(e) {         _this._canceled(e, _this);     });     xhr.upload.addeventlistener("loadstart", function(e) {         _this._start(e, _this);     });     xhr.open("post", this.assetbuilder.url);     xhr.send(this._formdata(asset)); } 

is there way queued files call progress function in safari can update ui progress bar?