Node.js can't handle my client code that performs something similar to jQuery/Zepto XHR pattern below:
$.ajax({
type: 'POST',
url: '/someUrl',
success: function(response) {
$.ajax({ // ... do another XHR
I've done this (initiating an XHR request within another XHR request) pattern before within other frameworks. I've read about Node.js Error: Can't set headers after they are sent and how the event-based model of Node.js server works. In other words, the first XHR request hasn't called res.end() so when the second XHR request is called Node.js complains (in a continuous loop btw).
My questions are: Would anyone be able to recommend an alternative pattern to chaining XHR requests client-side? Is there something I can do Node.js server-side to keep the existing client-side pattern?
Update Based On Accepted Answer
The mistake is certainly in my own server side code. A simple validation function was throwing an error but upon catching it, only res.end() was called. For some reason the assumption I had was calling res.end() would immediately stop the execution of the function. In this case, inserting a 'return' stops execution immediately after sending the JSON message to the client.
if (_.isEmpty(req.body)) {
res.end(JSON.stringify({'Error':'POST required'}));
// suppose 'return' is needed here as well
return
} else {
try {
if (_.has(req.body, 'id')) {
id = parseInt(req.body['id']);
} else {
throw {'Error':'Missing param in req.body'};
} // end if
} catch(err) {
res.end(JSON.stringify({'Error':'Missing key(s)','Keys':_.keys(req.body)}));
// without a return here, the code below this 'do some more work' would
// be executed
return
} // end else
// do some more work
// without the above 'return''s the code would
// a) make a database call
// b) call res.end() again!!! <-- bad.
successcallback is called once all of the data has been transmitted by the server, so the Noderesponseobject should have already been closed to reach that point, and the second AJAX call shouldn't have an impact. – Championship