Error:can ' t set headers after they is sent.

Problem Description:

System: Windows 7 x64

node. JS Version: Version is: v4.2.4 LTS

Installation process reference: "Getting Started with node. js" in Windows 7 node. JS Web Development Environment Build notes

The code for a backend impersonation HTTP request appears with the following error: Error:can ' t set headers after they is sent.

Such as:

Related code:

App.get ('/trans ', function (req, res) {var body = ';//This is the data to be submitted params = {' source ': ' en ', ' target ': ' es ', ' text ': ' Hello '}v AR data = qs.stringify (params); Http.get ("Https://gateway.watsonplatform.net/language-translation/api/v2/translate ? "+ data, function (Gres) {console.log (" Got response: "+ gres); Gres.on (' Data ', function (d) {body + = D;}). On (' End ', function () {  //console.log (gres.headers);  Console.log (body);  Res.send (body); });}). On (' Error ', function (e) {console.log ("Got error:" + e.message);}); Res.send (body);});

cause of the problem:

The cause of this error occurs because

Http.get

The response code in is asynchronous,

But before it responds, it is the bottom sentence, "res.send (body);" The response flow has been closed.

Workaround:

will be the bottom of the sentence "res.send (body);" The comment is OK.

Error:can ' t set headers after they is sent.