client/js/upload-handler/xhr.upload.handler.js
function(id, optChunkIdx, xhr, optAjaxRequester) {
            var xhrsId = optChunkIdx == null ? -1 : optChunkIdx,
                tempState = handler._getFileState(id).temp;

            tempState.xhrs = tempState.xhrs || {};
            tempState.ajaxRequesters = tempState.ajaxRequesters || {};

            tempState.xhrs[xhrsId] = xhr;

            if (optAjaxRequester) {
                tempState.ajaxRequesters[xhrsId] = optAjaxRequester;
            }

            return xhr;
        }
function(id, optChunkIdx, xhr, optAjaxRequester) {
            var xhrsId = optChunkIdx == null ? -1 : optChunkIdx,
                tempState = handler._getFileState(id).temp;

            tempState.xhrs = tempState.xhrs || {};
            tempState.ajaxRequesters = tempState.ajaxRequesters || {};

            tempState.xhrs[xhrsId] = xhr;

            if (optAjaxRequester) {
                tempState.ajaxRequesters[xhrsId] = optAjaxRequester;
            }

            return xhr;
        }
function ( id , optChunkIdx , xhr , optAjaxRequester ) { var xhrsId = optChunkIdx == null ? - 1 : optChunkIdx , tempState = handler . _getFileState ( id ) . temp ; tempState . xhrs = tempState . xhrs || { } ; tempState . ajaxRequesters = tempState . ajaxRequesters || { } ; tempState . xhrs [ xhrsId ] = xhr ; if ( optAjaxRequester ) { tempState . ajaxRequesters [ xhrsId ] = optAjaxRequester ; } return xhr ; }
Registers an XHR transport instance created elsewhere.

@param id ID of the associated file
@param optChunkIdx The chunk index associated with this XHR, if applicable
@param xhr XMLHttpRequest object instance
@param optAjaxRequester `qq.AjaxRequester` associated with this request, if applicable.
@returns {XMLHttpRequest}
Registers an XHR transport instance created elsewhere .