Not quite understand your question.. Generally speaking, Javascript application use a Promise object for deferred and asynchronous operation. For example , do something when two or more asynchronous operations completed (in any order). Qt do not bundle any Promise implementation by default. You could get a one from my github repo: benlau/quickpromise Example Promise { resolveWhen: Q.all([endpoint1. onReplyStatusChanged,endpoint2. onReplyStatusChanged]); onFulfilled: { // It will be triggered only if both of the endpoint emitted the signal controller.setData1(); controller.setData2(); } }