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Get and check a value from JSON read in NodeJS

I'm trying to check if a user exists (registered on a json file).
Unfortunately I don't find a valid solution in all Stack Overflow that gives me a simple "true" in a callback.
The version closest to a solution
Experiment V1 :
let userExist;
function check(){
console.log("CHECK!");
return userExist = true;
}
// check(); if this, return true... obvious.
//// check if user exist
server.readFileSync(filepath, 'utf8', (err, data) =>
{
let json = JSON.parse(data),
userlist = json.allusers;
for (let key in userlist)
{
if ( userlist[key].email == req.body.user_email )
{
console.log("FINDED EQUAL");
check(); // return undefined ???
}
}
});
console.log("userExist value : "+userExist);
differently formulated the debugs also appear, but "true" never returns.
note: yes, JSON is read correctly. If everything works inside the readfile, you immediately notice the same emails.
output: "undefined"
Log: total bypassed
Experiment V2 :
In this case (with asynchronous reading) it returns all the debugging (but the "true" remains undefined)
The problem with the asynchronous is that I have to wait for it to check to continue with the other functions.
//// check if user exist
server.readFile(filepath, 'utf8', (err, data) =>
{
let json = JSON.parse(data),
userlist = json.allusers;
for (let key in userlist)
{
if (/* json.allusers.hasOwnProperty(key) &&*/ userlist[key].email == req.body.user_email )
{
console.log("FINDED EQUAL");
check();
}
}
});
var userExist;
function check(userExist){
console.log("CHECK!");
return userExist=true;
}
console.log("userExist value : "+userExist+"");
server listening on: 8080
userExist value : undefined
CHECK!
FINDED EQUAL
Experiment V3 :
after the various suggestions I come to a compromise by using the syntax for the async functions.
This allowed to reach an ordered code, but despite this it is not possible to wait for the results and export them out of the same function (this is because node itself is asynchronous! Therefore it has already gone on!)
using a "message" variable to check if it could return an object I did so:
//simple output tester
var message;
// create a promise
let loopusers = new Promise( (resolve)=>{
server.readFile( filepath, 'utf8',
(err, data) => {
let json = JSON.parse(data),
userlist = json.allusers,
findedequal;
console.log("CHECK USERS IN DB...for "+userlist.length+" elements");
// loop all items
for (let key in userlist)
{
console.log("Analyzed key ::: "+key);
if ( userlist[key].email == req.body.user_email )
{
console.log("CHECK : user isn't free");
findedequal=true;
resolve(true); // return the result of promise
}
else if(key >= userlist.length-1 && !findedequal )
{
console.log("CHECK : User is free ;)");
resolve(false); // return the result of promise
}
}
// call the action
createuser();
});
});
// when promise finished --> start action
async function createuser(message)
{
let userExist = await loopusers;
console.log("userExist: "+userExist);
if(userExist)
{
message = { Server: "This user already exists, Try new e-mail..."};
}
else
{
message = { Server: "Registration user -> completed..."};
}
// return values
return message;
};
It is also possible to use the classic syntax via "then". For exemple:
//simple output tester
var message;
// create a promise
let loopusers = new Promise( (resolve)=>{
...
});
loopusers.then( (response)=>{
...
})
Then I realized that it was easy to simplify even more by calling the functions directly from the initial one:
var message;
// create a promise --> check json items
server.readFile( filepath, 'utf8',
(err, data) => {
let json = JSON.parse(data),
userlist = json.allusers,
findedequal;
console.log("CHECK USERS IN DB...for "+userlist.length+" elements");
for (let key in userlist)
{
console.log("Analyzed key ::: "+key);
if ( userlist[key].email == req.body.user_email )
{
console.log("CHECK : user isn't free");
findedequal=true;
createuser(true); // call direct function whit params true
}
else if(key >= userlist.length-1 && !findedequal )
{
console.log("CHECK : User is free ;)");
createuser(false); // call direct function whit params false
}
}
});
// start action
function createuser(userExist)
{
if(userExist)
{
message = { Server: "This user already exists, Try new e-mail..."};
}
else
{
message = { Server: "Registration user -> completed!"};
}
// return values
return message;
};
debugging is taken and written
the message is lost outside the aSync function
Experiment V4 Final! :
Finally, after many attempts the solution! (Yes... But know it's not Async)
If we allocate in a variable the reading becomes synchronous the whole model and we return to the simple one
let message,
file = server.readFileSync(filepath, 'utf8'), // read sync
json = JSON.parse(file), // now parse file
userlist = json.allusers, // get your target container object
userExist,
findedequal;
console.log("CHECK USERS IN DB...for "+userlist.length+" elements");
for (let key in userlist)
{
console.log("Analyzed key ::: "+key);
if ( userlist[key].email == req.body.user_email )
{
console.log("CHECK : finded equal value on key ["+key+"] - user isn't free");
findedequal=true;
userExist = true;
}
else if(key >= userlist.length-1 && !findedequal )
{
console.log("CHECK : User is free ;)");
userExist = false;
}
}
if(userExist)
{
console.log("└ EXIT TO CHECK --> Can't create user, function stop.");
message = { Server: "This user already exists, Try new e-mail..."};
}
else
{
console.log("└ Exit to check --> New user registration ...");
message = { Server: "Registration user -> completed!"};
}
}
return message;
Now:
It's all sync and all log is perfect
all var is checked
all return... return
** Final conclusions: **
Is it possible to retrieve an ASync variable in node?
As far as I understand so far ... no.
Node is async by its nature, therefore recovering information that is not saved and then recovered from a DB is left behind among the things to do, becoming unrecoverable if you use it as in this post.
However ... if the purpose is to make reading a file synchronous, the answer was simpler than expected.
A special thanks to: Barmar; Austin Leehealey; C.Gochev;

The problem is that you are calling console.log("userExist value : "+userExist+"");
too early. At the moment that you call that line, userExist is not defined yet. This is because the server.readFile() function requires a callback and that callback function is executed once it has read the file. However, reading files often take time and so the program keeps going. It executes console.log("userExist value : "+userExist+""); and then goes back to the callback function and defines userExist as true.
If you want more information on what callbacks are look at the link below. Callbacks are a defining feature of Nodejs and understanding them is essential to any Node website.
https://medium.com/better-programming/callbacks-in-node-js-how-why-when-ac293f0403ca
Try something like this.
let userExist;
function check(){
console.log("CHECK!");
return userExist = true;
}
// check(); if this, return true... obvious.
//// check if user exist
server.readFileSync(filepath, 'utf8', (err, data) =>
{
let json = JSON.parse(data),
userlist = json.allusers;
for (let key in userlist)
{
if ( userlist[key].email == req.body.user_email )
{
console.log("FINDED EQUAL");
check(); // return undefined ???
console.log("userExist value : "+userExist);
}
}
});

Firebase value is undefined when it is not supposed to be

I am working on a firebase project. During testing the
return user.val().name;
will return an
undefined
value however the
console.log(user.val().name)
will return the actual string stored in the .name field. Why is that. Also even if assign the
user.val().name
to a variable, the variable remains undefined.Please help figure out why this happens. I am printing it to a csv.
Here is my code:
var database = firebase.database();
var ref2 = database.ref('information/');
var id;
var name;
ref2.on("value", function (one) {
one.forEach(function (two) {
if (typeof two.val().Id !== 'undefined') {
id = two.val().Id;
name = program(id); //name undefined
}
else {
id = "";
}
csv = name + "," + id +"\n";
});
download(csv);
});
};
function program (id) {
var database = firebase.database();
var ref = database.ref("users/" + id + "/");
ref.on('value',function(user){
if (typeof user.val().name === 'undefined') {
return null;
}
else {
console.log(user.val().name); //this doesnt show undefined
return user.val().name; //this shows undefined when appended to a html element
}
})
}
Note: In the firebase database, the name value is not null. It has a string added to it.

I second with Frank's reason on why your function program() doesn't work. Because ref.on('value'... makes an asynchronous call, program() does not wait for the completion of ref.on and exists with an undefined return value.
What you could instead do is use Promises. Wrap the statements inside your program() function within a Promise, and upon completion of the asynchronous call, resolve or reject based on the result it gives.
Here's your function with Promises:
function program(id) {
return new Promise(function (resolve, reject) {
try {
var database = firebase.database();
var ref = database.ref("users/" + id + "/");
ref.on('value', function (user) {
if (typeof user.val().name === 'undefined') {
resolve(null);
} else {
console.log(user.val().name);
resolve(user.val().name);
}
})
} catch (e) {
reject(e)
}
});
}
And then, here's how you can read the result:
program(id).then(function (result) {
console.log(result)
//Do what you want with the result here
}).catch(function (error) {
console.log(error)
})
Note: You're executing this block in a for-each statement. If you're using Promises, you'd also need to look into how to use Promises inside a loop. For reference, check Promise.all()

Most likely you are trying to use the returned name in the code that calls your program function. E.g.
var name = program("1234");
console.log(name); // this will print undefined
This will not work, since your program() is not actually returning name. Data is loaded from Firebase asynchronously. By the time program() exits, the data isn't loaded yet.
This is easiest to see by putting a few log statements into the code:
function program (id) {
var database = firebase.database();
var ref = database.ref("users/" + id + "/");
console.log("Before attaching listener");
ref.on('value',function(user){
console.log("Got value from database");
})
console.log("After attaching listener, exiting function");
}
This will print:
Before attaching listener
After attaching listener, exiting function
Got value from database
This is likely not the order that you expected, but it is working as designed. Instead of waiting for the data to be loaded (and making the browser/user wait), your code continues. Then when the data is loaded, your callback is invoked. But in your original code that means that your return statement is unable to return the name to the original caller.
This is precisely the reason why the Firebase Database (and most web APIs) use callbacks like the one you pass into on(). This callback is invoked when the data is available and is the only place where you can access the user data. So any code that requires the data you just loaded must be inside that callback, or be called from inside that callback. E.g.
function program (id) {
var database = firebase.database();
var ref = database.ref("users/" + id + "/");
ref.on('value',function(user){
if (typeof user.val().name === 'undefined') {
return null;
}
else {
console.log(user.val().name);
appendToHtmlElement(user.val().name);
}
})
}

Firebase> DataBase> Role
Have you changed the value of rules?
Comment Example!
That can get the value after moving to name.
var ref = database.ref ("users/" + id + "/name");
ref.on ('value', function (user) {
    if (user.val ()! = null) {
         console.log (user.val ())
     }
}
If not, let's worry about it.

You should receive the returned value.
var name = ref.on('value',function(user){
if (typeof user.val().name === 'undefined') {
return null;
}
else {
console.log(user.val().name); //this doesnt show undefined
return user.val().name; //this shows undefined when appended to a html element
}
})
then use return name to get the value. or simply return the return ref.on('value' ...

Parse Cloud Code: Logic Branching in Promises

I'm trying to write a Parse.com Cloud Code function to accomplish the following workflow:
User submits a value.
Cloud code function checks to see if that value matches any objects of type code.
If not, the function returns a "not found" value.
If so, the object of type code is assumed to have a pointer to an object of type item.
Then, code.item is checked to see whether it has a pointer to an object of type alert.
If not, the function returns a "not found" value.
If code.item.alert does exist, then I want to fetch the full alert object, including pointers which may or may not exist, up to 2 layers deep.
As I begin writing the code for this function, I can get it working to the point of checking to see whether the code exists and, if so, whether code.item.alert also exists.
This is where the problem arises. As it currently stands, in the working version of my function, the alert item that is returned is only the class type and objectId. I understand why that is happening, and I am trying to write code to populate the object before returning it, but I am failing in that attempt.
Here's the code that is working so far (but only returning the alert object's shell):
Parse.Cloud.define("alertLookup", function (request, response) {
Parse.Cloud.useMasterKey();
var codeQuery = new Parse.Query("code");
codeQuery.equalTo("value", request.params.code);
codeQuery.include("item");
codeQuery.find().then(function (codes) {
if (codes.length === 0) {
response.success("no item");
} else {
var code = codes[0];
var item = code.get("item");
var alert = item.get("alert");
if (alert === null || alert === undefined) {
response.success("no item");
} else {
response.success(alert);
}
}
}, function (error) {
response.error(error);
});
});
Here's what I have tried that is failing with an error code of 141:
Parse.Cloud.define("alertLookup", function (request, response) {
Parse.Cloud.useMasterKey();
var codeQuery = new Parse.Query("code");
codeQuery.equalTo("value", request.params.code);
codeQuery.include("item");
codeQuery.find().then(function (codes) {
if (codes.length === 0) {
response.success("no item");
} else {
var code = codes[0];
var item = code.get("item");
var alert = item.get("alert");
if (alert === null || alert === undefined) {
response.success("no item");
} else {
return alert.fetch();
}
}
}).then(function (a) {
response.success(a);
}, function (error) {
response.error(error);
});
});
Why won't the fetch() call work properly? When I insert console.log() statements, although alert is non-null, return alert.fetch(); does not ever seem to be called. At least, the response.success(a); line is never called. Why not?

Try this instead while chaining Promises:
codeQuery.find().then(function (codes) {
if (codes.length != 0) {
var code = codes[0];
var item = code.get("item");
var alert = item.get("alert");
if (alert != null && alert != undefined) {
var alertObj = new Parse.Object("alert"); // alert class ???
alertObj.id = alert.id;
return alertObj.fetch();
}
}
// return a Promise for no items
return Parse.Promise.as("no item");
}).then(function (a) {
response.success(a);
}, function (error) {
response.error(error);
});

Unreliable behaviour in Node.js

I have a Node.js application that, upon initialisation, reads two tables from an SQL database and reconstructs their relationship in memory. They're used for synchronously looking up data that changes (very) infrequently.
Problem: Sometimes I can't access the data, even though the application reports successfully loading it.
Code:
constants.js
module.exports = {
ready: function () { return false; }
};
var log = sysLog('core', 'constants')
, Geo = require('../models/geo.js');
var _ready = false
, _countries = []
, _carriers = [];
function reload() {
_ready = false;
var index = Object.create(null);
return Geo.Country.find().map(function (country) {
var obj = country.toPlainObject()
, id = obj.id;
delete obj.id;
index[id] = obj;
return Object.freeze(obj);
}).then(function (countries) {
log.debug('Loaded ' + countries.length + ' countries');
_countries = countries;
return Geo.Carrier.Descriptor.find().map(function (carrier) {
var obj = carrier.toPlainObject();
if (obj.country) {
obj.country = index[obj.country];
}
return Object.freeze(obj);
}).then(function (carriers) {
log.debug('Loaded ' + carriers.length + ' carriers');
_carriers = carriers;
});
}).finally(function () {
_ready = true;
});
}
reload().catch(function (err) {
log.crit({ message: 'Could not load constants', reason: err });
process.exit(-42);
}).done();
module.exports = {
reload : reload,
ready : function () { return _ready; },
countries : function () { return _countries; },
carriers : function () { return _carriers; }
};
utils.js
var log = sysLog('core', 'utils')
, constants = require('./constants');
module.exports = {
getCountryByISO: function(iso) {
if (!iso) {
return;
}
if ('string' != typeof iso) {
throw new Error('getCountryByISO requires a string');
}
if (!constants.ready()) {
throw new UnavailableError('Try again in a few seconds');
}
switch (iso.length) {
case 2:
return _.findWhere(constants.countries(), { 'iso2' : iso.toUpperCase() });
case 3:
return _.findWhere(constants.countries(), { 'iso3' : iso.toUpperCase() });
default:
throw new Error('getCountryByISO requires a 2 or 3 letter ISO code');
}
},
getCarrierByCode: function(code) {
if (!code) {
return;
}
if ('string' != typeof code) {
throw new Error('getCarrierByCode requires a string');
}
if (!constants.ready()) {
throw new UnavailableError('Try again in a few seconds');
}
return _.findWhere(constants.carriers(), { 'code' : code });
},
getCarrierByHandle: function(handle) {
if (!handle) {
return;
}
if ('string' != typeof handle) {
throw new Error('getCarrierByHandle requires a string');
}
if (!constants.ready()) {
throw new UnavailableError('Try again in a few seconds');
}
return _.findWhere(constants.carriers(), { 'handle' : handle });
}
};
Use case
if (data.handle) {
carrier = utils.getCarrierByHandle(data.handle);
if (_.isEmpty(carrier)) {
throw new InternalError('Unknown carrier', { handle: data.handle });
}
}
What's going on: All errors are logged; as soon as I see an error (i.e. "Unknown carrier") in the logs, I check the SQL database to see if it should've been recognised. That has always been the case so far, so I check the debug log to see if data was loaded. I always see "Loaded X countries" and "Loaded Y carriers" with correct values and no sign of "Could not load constants" or any other kind of trouble.
This happens around 10% of the time I start the application and the problem persists (i.e. didn't seem to go away after 12+ hours) and seems to occur regardless of input, leading me to think that the data isn't referenced correctly.
Questions:
Is there something wrong in constants.js or am I doing something very obviously wrong? I've tried setting it up for cyclical loading (even though I am not aware of that happening in this case).
Why can't I (sometimes) access my data?
What can I do to figure out what's wrong?
Is there any way I can work around this? Is there anything else I could to achieve the desired behaviour? Hard-coding the data in constants.js is excluded.
Additional information:
constants.reload() is never actually called from outside of constants.js.
constants.js is required only in utils.js.
utils.js is required in app.js (application entry); all files required before it do not require it.
SQL access is done through an in-house library built on top of knex.js and bluebird; so far it's been very stable.
Versions:
Node.js v0.10.33
underscore 1.7.0
bluebird 2.3.11
knex 0.6.22

}).finally(function () {
_ready = true;
});
Code in a finally will always get called, regardless of if an error was thrown up the promise chain. Additionally, your reload().catch(/* ... */) clause will never be reached, because finally swallows the error.
Geo.Country.find() or Geo.Carrier.Descriptor.find() could throw an error, and _ready would still be set to true, and the problem of your countries and carriers not being set would persist.
This problem would not have occurred if you had designed your system without a ready call, as I described in my previous post. Hopefully this informs you that the issue here is really beyond finally swallowing a catch. The real issue is relying on side-effects; the modification of free variables results in brittle systems, especially when asynchrony is involved. I highly recommend against it.

Try this
var log = sysLog('core', 'constants');
var Geo = require('../models/geo.js');
var index;
var _countries;
var _carriers;
function reload() {
index = Object.create(null);
_countries = Geo.Country.find().map(function (country) {
var obj = country.toPlainObject();
var id = obj.id;
delete obj.id;
index[id] = obj;
return Object.freeze(obj);
});
_carriers = _countries.then(function(countries) {
return Geo.Carrier.Descriptor.find().map(function (carrier) {
var obj = carrier.toPlainObject();
if (obj.country) {
obj.country = index[obj.country];
}
return Object.freeze(obj);
});
});
return _carriers;
}
reload().done();
module.exports = {
reload : reload,
countries : function () { return _countries; },
carriers : function () { return _carriers; }
};

constants.reload() is never actually called from outside of
constants.js.
That's your issue. constants.reload() reads from a database, which is an aysnchronous process. Node's require() is a synchronous process. At the time constants.js is required in utils.js and the module.exports value is returned, your database query is still running. And at whatever point in time that app.js reaches the point where it calls a method from the utils module, that query could still be running, resulting in the error.
You could say that requiring utils.js has the side-effect of requiring constants.js, which has the side-effect of executing a database query, which has the side-effect of concurrently modifying the free variables _countries and _carriers.
Initialize _countries and _carriers as unresolved promises. Have reload() resolve them. Make the utils.js api async.
promises.js:
// ...
var Promise = require('bluebird');
var countriesResolve
, carriersResolve;
var _ready = false
, _countries = new Promise(function (resolve) {
countriesResolve = resolve;
})
, _carriers = new Promise(function (resolve) {
carriersResolve = resolve;
});
function reload() {
_ready = false;
var index = Object.create(null);
return Geo.Country.find().map(function (country) {
// ...
}).then(function (countries) {
log.debug('Loaded ' + countries.length + ' countries');
countriesResolve(countries);
return Geo.Carrier.Descriptor.find().map(function (carrier) {
// ...
}).then(function (carriers) {
log.debug('Loaded ' + carriers.length + ' carriers');
carriersResolve(carriers);
});
}).finally(function () {
_ready = true;
});
}
reload().catch(function (err) {
log.crit({ message: 'Could not load constants', reason: err });
process.exit(-42);
}).done();
module.exports = {
reload : reload,
ready : function () { return _ready; },
countries : function () { return _countries; },
carriers : function () { return _carriers; }
};
utils.js
getCarrierByHandle: function(handle) {
// ...
return constants.carriers().then(function (carriers) {
return _.findWhere(carriers, { 'handle' : handle });
});
}
Use case:
utils.getCarrierByHandle(data.handle).then(function (carrier) {
if (_.isEmpty(carrier)) {
throw new InternalError('Unknown carrier', { handle: data.handle });
}
}).then(function () {
// ... next step in application logic
});
This design will also eliminate the need for a ready method.
Alternatively, you could call constants.reload() on initialization and hang all possibly-dependent operations until it completes. This approach would also obsolete the ready method.
What can I do to figure out what's wrong?
You could have analyzed your logs and observed that "Loaded X countries" and "Loaded Y carriers" were sometimes written after "Unknown carrier", helping you realize that the success of utils.getCarrierByHandle() was a race condition.

Javascript Array Losing an Element At Random

I have a very strange issue that I am running into. I am using jsTree from JQueryUI on one of my sites, and I have different implementations of it used in different .js files. One of them seems to work, which is very confusing as it uses almost identical code (only the variable names are different) to the implementation that is broken. The problem comes from the contextmenu function. The code I am using is as follows:
$(document).ready(function () {
if(typeof dryerList == 'undefined' || dryerList.length == 0) {
var dryerList = [];
$.ajax({
url:'../TrackingApp/getGrainBins.php?t=234.23423452353',
async: false,
success: function(text) {
try {
dryerList = $.parseJSON(text);
} catch (e) {
alert('ERROR: ' + e);
}
if(dryerList.length == 0) {
alert('ERROR: No fleet data received.')
}
}
});
}
$("#dryerListTree").jstree({
plugins : ['json_data', 'ui', 'themes', 'contextmenu'],
contextmenu: {items: customBinMenu},
json_data : { data: binNodes }
});
$('#dryerListTree').bind("dblclick.jstree", function (event) {
var node = $(event.target).closest("li");
var id = node[0].id;
for(i=0; i < dryerList.length; i++) {
if(id == dryerList[i].id) {
centerMap(dryerList[i].y, dryerList[i].x);
break;
}
}
});
});
function customBinMenu(node) {
if ($(node).hasClass("folder")) {
return;
}
var items = {
centerItem: {
label: "Locate",
action: function () {
// Centers map on selected bin
var id = node[0].id;
for(i=0; i < dryerList.length; i++) {
if(id == dryerList[i].id) {
centerMap(dryerList[i].y, dryerList[i].x);
break;
}
}
}
},
dashboardItem: {
label: "Dashboard",
action: function () {
// Opens dryer info window over map
var id = node[0].id;
var dryerIndex = -1;
for(i=0; i < dryerList.length; i++) {
if(id == dryerList[i].id) {
dryerIndex = i;
break;
}
}
}
}
};
return items;
}
The strange bit is, the double-click handler works just fine. When I get to the customBinMenu() function, the dryerList array is there, and dryerList[0] contains 4 of the 5 values that it should- but somehow the 'id' element has been dropped from that object. I have been looking at this for quite some time, and I can't figure out how it can drop a single element from the object without losing any other data, especially when identical code is working for a similar list. Any suggestions?

Ok, I read in your question: 'and dryerList[0] contains 4 of the 5 values that it should- but somehow the 'id' element has been dropped from that object'
So by 'element' and 'value' I assume you mean 'attribute': the node's 'id'-attribute to be precise ??
I see in your code: var id = node[0].id;
That should be: var id = node[0].getAttribute("id");
Good luck!
UPDATE 1:
Ok, if (as per your comment) var id = node[0].id; (getting id from node[0]) is ok, then if(id == dryerList[i].id) looks wrong, since you just (re-)defined id to be the value of node[0]'s id.
Actually I would not use 'id' as a var-name (in this case).
So what if you did: var idc = node[0].getAttribute("id");
and then: if(idc === dryerList[i].getAttribute("id"))
UPDATE 5: You still have some errors by the way:
You forgot a semi-colon to close the alert in:
if(dryerList.length == 0) {
alert('ERROR: No fleet data received.')
}
You should use '===' to compare with '0' on line 2 and 14
naturally in real life you would define function customBinMenu(node) before it was used in your document.ready function.
Fixed by swapping code order.
The same goes for this document.ready function where you used var dryerList before it was defined.
Fixed by: var dryerList = dryerList || []; if(dryerList.length === 0){//ajax & json code}
Could you please confirm if this fiddle, which is now valid javascript, represents your intended baseline-code that still results in your problem of the 'id'-attribute being 'undefined' in dryerList's node-collection (since the code you posted contained some simple errors that are fixed in this jsfiddle, excluding the things mentioned in update 1, since you commented that this is not the problem) ?
May I ask (since you start at document.ready), why do you (still) check if dryerList already exists?
May I ask if you could update that corrected fiddle with some demo-data for us to toy around with?