javascript - Variable not updating properly -

this relevant code :

this sends request server, takes username argument.

function send_client_lookup(username) {     send(         auth.aocp.client_lookup,         [ [ 's', username.tostring() ]         ]     )  } 

this part handles response server.

handle[auth.aocp.client_lookup] = function (data, u)         {         console.log('client_lookup')         var userid = u.i()         var username = u.s()         u.done()         console.log({ userid : userid, username : username })   // works         var idresult = userid; // can use userid assigned idresult make code easier understand.         } 

the above 2 functions work how supposed to, nothing change/fix there.

now have function receives request 1 user , sends request user, takes 2 arguments: first arg userid of user sends request , second username of user request sent server/game works userids username has converted:

var commands = {     invite: function(userid, username) {         send_client_lookup(username); // send request server find out userid of username         send_privgrp_invite(idresult);      }  } 

the problem idresult == undefined, unless call cmd.invite() again idresult == 'with previous response this:

cmd.invite(user1); cmd.invite(user2); cmd.invite(user3); 

and output of idresult is:

idresult == undefined idresult == 'info user1' idresult == 'info user2' 

i tried defining idresult outside response handler , update inside, make sure not sort of delay server did massive invite spam , result same, 1 step behind no matter how fast sent invites. suggestions welcome :)

the problem rather hard solve, sending , collecting replies isolated. seems send() sends packet , handle() receives reply, , there can many possible unrelated packets between sending , receiving.

if it's case special global map should created link requests , responses. cases when there 2 concurrent requests same username, eventemitter events module fit, it's multimap of strings callbacks:

var events = require('events')  var outstandinglookups = new events.eventemitter() 

so when send lookup register 1 time listener, there's no need manual cleanup:

var commands = {     invite: function(username) {         outstandinglookups.once(username, function (idresult)         {             send_privgrp_invite(idresult);         })         // send request server find out userid of username         send_client_lookup(username);      }    } 

in response handler emit conveniently calls callbacks expecting userid received username:

handle[auth.aocp.client_lookup] = function (data, u) {         console.log('client_lookup')         var userid = u.i()         var username = u.s()         u.done()         console.log({ userid : userid, username : username })   // works         // can use userid assigned idresult         // make code easier understand.         var idresult = userid;           // addition original handler code         outstandinglookups.emit(username, idresult) } 

the need use outstandinglookups.once implementation detail , should encapsulated/hidden if want lookup userids in more 1 place in code.

i use promises q npm library remember interface, similar es6 promises should used in production code modern standard.

var q = require('q')  var commands = {     lookupusername: function (username)     {         var result = q.defer()         outstandinglookups.once(username, function (idresult)         {             result.resolve(idresult);         })         // send request server find out userid of username         send_client_lookup(username);           return result.promise      },      invite: function(username) {         commands.lookupusername(username).then(function (idresult)         {             send_privgrp_invite(idresult);         })     }    } 

the code commands.invite cleaner now.