How can I return datas to Http Request?

Now I use a SIM7600CE for 4G connection. The modules didn't adapt for this kind of sim card.
So I have to write my own module for it.

Now I can get response datas in this Method:

recv: function (sckt, maxLen) {
    if (sockData[sckt]) {
      var r;
      console.log("recv", sockData[sckt].length);
      if (sockData[sckt].length > maxLen) {
        r = sockData[sckt].substr(0, maxLen);
        sockData[sckt] = sockData[sckt].substr(maxLen);
        console.log("recv", sockData[sckt]);
      } else {
        r = sockData[sckt];
        sockData[sckt] = "";
        console.log("recv | socks[sckt]", socks[sckt]);
        if (socks[sckt] == "DataClose") {
          dbg("Got DataClose - forcing close");
          socks[sckt] = "closing";
        }
      }
      console.log("[recv data]", r)
      return r;
    }
    if (socks[sckt] == "closing" || !socks[sckt]) return -1; // close it
    return "";
  },

I think this part is the place where return datas to http.get().
But I can't recieve any datas in this place.
Do you have any introductions about how the datas flow in the network?

http.get("http://www.pur3.co.uk/hello.txt", function (res) {
      let str = ''; 
      res.on('data', chunk => {
        console.log("chunk",chunk);
        str += chunk;
      });
      res.on('end', () => {
        console.log("result: --->   ", str);
      });
    });

Tue 2020.03.24

Has an attempt to place a console.log() statement just after the http.get request at L1a to see if anything is being detected/returned within the callback?
or use of the debugger?

Related content with fix

forum: http.request not working on Espruino Wifi

Could it be related to https

https://www.espruino.com/Internet#https

http://www.espruino.com/Internet

The code

console.log("back from network?",res)
didn't print anything.

tp.get("http://www.pur3.co.uk/hello.txt", function (res) {
     console.log("back from network?",res)
      let str = ''; 
      res.on('data', chunk => {
        console.log("chunk",chunk);
        str += chunk;
      });
      res.on('end', () => {
        console.log("result: --->   ", str);
      });
    });

In the Mehtod recv(), I did got datas and retruned them. But where these datas go I really don't know, and how do they go back to http.get response body?

console.log("[recv data]", r)

return r;

This might have the solution and a reasonable explanation:

'On the Internet page there is a simple example of sending data in the URL from a webpage, but it can be unreliable if anywhere between your browser and the Espruino decides to cache the received data.'

http://www.espruino.com/Posting+Forms

My suggestion is to post the response data in it's entirety so that others may take a look and compare to what should be in the response packet.

'how do they go back to'

Don't know but, could it be the use of the arrow functions not allowing binding to the http response object?

This is the request message

GET /hello.txt HTTP/1.1
User-Agent: Espruino 2v04.401
Connection: close
Host: http://www.pur3.co.uk

And this is the response message

RECV FROM:93.93.135.13:80
+IPD259
HTTP/1.1 200 OK
Date: Wed, 25 Mar 2020 02:30:54 GMT
Server: Apache/2.4.18 (Ubuntu)
Last-Modified: Fri, 15 Nov 2013 15:42:26 GMT
ETag: "d-4eb390b887c80"
Accept-Ranges: bytes
Content-Length: 13
Connection: close
Content-Type: text/plain
Hello World!
+IPCLOSE: 0,1

I tried to put debuggers in two places. In this place, I can't reach the debugger 2.

     debugger;  // 1
    http.get("http://www.pur3.co.uk/hello.txt", function(res) {
      debugger;  //2
      let str = ''; 
      res.on('data', chunk => {
        console.log("chunk",chunk);
        str += chunk;
      });
      res.on('end', () => {
        console.log("Get some test request contents: --->   ", str);
      });
    });

And the second place here:

recv: function (sckt, maxLen) {
    if (sockData[sckt]) {
      console.log("ddddddddddddddd",sockData[sckt])
      var r;
      console.log("recv", sockData[sckt].length);
      if (sockData[sckt].length > maxLen) {
        r = sockData[sckt].substr(0, maxLen);
        sockData[sckt] = sockData[sckt].substr(maxLen);
        console.log("recv", sockData[sckt]);
      } else {
        r = sockData[sckt];
        sockData[sckt] = "";
        console.log("recv | socks[sckt]", socks[sckt]);
        if (socks[sckt] == "DataClose") {
          dbg("Got DataClose - forcing close");
          socks[sckt] = "closing";
        }
      }
      console.log("[recv data]", r);
      debugger; // 3
      return r;
    }
    if (socks[sckt] == "closing" || !socks[sckt]) return -1; // close it
    return "";
  },

I can reach debugger 3. And then where the code goes puzzle me so much! What's the relation between Http.get() and recv()?

debug>step

          return r;
          ^

debug>step
Value returned is ="Hello World!"

Tue 2020.03.24

It is working as expected as text 'Hello World!' is returned.

As at L20 the string is available in local scope, why not assign it to a global var at that point?

Better:

POST not GET

See link in post #4 and:

http://www.espruino.com/Internet

Concept

https://developer.mozilla.org/en-US/docs/Mozilla/js-ctypes/Using_js-ctypes/Declaring_and_Using_Callbacks

https://codeburst.io/javascript-what-the-heck-is-a-callback-aba4da2deced

https://www.dashingd3js.com/lessons/javascript-callback-functions

https://stackoverflow.com/questions/5263785/how-to-use-callback-function-in-java-script-functions